I have a Rad Wagon 4 (my wife's), a Rad Runner, and a Kona Brewing Beach cruiser I turned electric.

I have lots of hills in my area and upgraded all my ebikes.

Rad Wagon - Area 13 Ebikes (or electrobikeworld.com) 35 amp controller with color display.  $225 bucks. 1600 watts of power. **Best Upgrade**
I did the motor swap just recently as it was collecting dust and when I changed tires I swapped it. See youtube videos (a few of them). Easy to insert the motor. Barely noticeable, but slightly better. Very slightly.
Rad Wagon runs 2 batteries (48v) I did myself mounting on bottle cage screws. "No DateX" needed for same voltage. My Rad Runner has 3 x 48v batts in parallel. 2 years and no issues. I charge through one port unless I am in a rush then separately.

Next best upgrade - Get hydraulic Brakes. Magura, Sram, Tektro, Shimano. And opt for a larger front rotor. Original rear brake would never be able to lock up rear tire.

Tires. - Motorcycle tire. Yeah its heavier. Amazon reviews rave about these and I put them on instead of waiting for the recall as I could see my innertube ever so slightly I was scared to ride with the kids. MMG Tire 2.75-18 Front or Rear Motorcycle Dual Sport On or Off Road ... There are a couple others people like. I chose these and love them. https://amzn.to/3GnbW9B

Rear pads - Go on Etsy.com  OC Cafe Racer or search Rad Wagon seats. The OC Cafe Racer seats are awesome quality and I will put them on my Rad Runner when I have money to splurge.

*Keep the wooden rear decks. You will need to mount the larger controller underneath the spot it is currently in so the cables reach. You can cut one of those decks to use for mounting and a clean look. Need jigsaw etc. wood tools. And now I keep a small bag in that area for gloves and keys and water etc.

Hope this helps if you have a Rad Wagon 4.

Cheers!

Can't be too safe...it does happen. I run 3 batteries in parallel but have name brand batteries. I would be scared to buy from Alibaba/Aliexpress. If I did I would use more precaution when charging.

I use the Magura MT7e. I have experience with my old Ariel Rider dual motor using Tektro Hydraulics. Both have great stopping power. Magura has an amazing feel. Can use one finger on the lever with confidence. Hydraulics all the way. Use a larger rotor on the front if you want for a bit better performance and less heat.

Flying away....

I assume you have this motor and I have this one on my Rad Runner 2 - https://eunorau-ebike.com/products/bafang-fat-bike-48v1000w-rear-hub-screw-freewheel-motor

I recommend this which is on my wifes rad wagon and it is plug and play. You will need to get creative mounting the large controller box. - https://area13ebikes.com/products/radkit

Up to 1600 watts and way better climbing hills. Will use more battery obviously depending on how often you go full throttle.

My Rad Runner 2 has a setup built from parts at ebike.ca and it is way more geeky and more expensive. But the baserunner and phaserunner controllers are very small so mounting will be easier on the small mini frame. Rad Wagon is huge. They also have the motor on their site with the newer L10 motor cable. I would have bought the G62 motor from ebikes.ca but they did not sell it there 2 years ago. Sounds like you have the motor ready.

Good luck.

I did the Area13 swap on wife's rad wagon. Love it. It climbs hills better than my geeky Rad Runner 2 with Grin Tech setup using 1600+ watts on a G62 Bafang 1000w (I win on top speed hitting 29mph with Grin Tech controller Field Weakening option). I have yet to swap the radwagon motor for the 750w I have still in the box. Figure I will wear out the stock one for another year or 1000 miles more. Note, more power only adds a bit of more speed due to motor winding is the limiting factor. But climbing hills is way better. Naturally you will use more battery. My wifes rad wagon battery bms would cut out so I gave her my battery for Rad runner and I run 3 batteries in parallel so no issue. And I have now installed her a 2nd battery in parallel. We have hills to climb coming back from the beach loaded with kids on the bike and I don't like to pedal much.

*so the upgrade will push close to the stock battery limit. Obviously her battery has a bad cell or two that would not be noticed at stock controller maxing out at 749watts. But at 1600 watts you will know if you have a good battery or not

-Highly recommend upgrading to a good set of hydraulic brakes. I opted for Magura MT7e. You will be averaging a faster speed with more power because you reach 24mph a lot quicker.

I am running 3 batteries in parallel. The team at Grin Tech (ebikes.ca) said I do not need a balancer box since they are all 48v. Assume you need that if voltage is different, but then you run off the lower voltage anyway. They were right. over 1200 miles and not a single issue. The 2nd battery (14ah) hides in the center storage box of the rad runner 2 and I have a huge plastic crate from Uline as a basket holding a 3rd battery (reention 11.9ah) that one has the bms turning it off after a few min of bike off so I can press the button on it to turn it on if I want. And I regularly charge all 3 from the stock battery. I know some say this is wrong. But no issues with heat or anything. I can also charge all three separately if I am pressed on time.

Hope this helps... The 2 extra batteries are good quality from salvaged rental city bikes that people rent at stations hence I got them for a great deal. Believe they came from Vancouver. They are not knock off Alibaba kind. Meaning, there is always a risk of fire with lithium batteries. Safer to not leave plugged in overnight or park bike away from flammable objects.

-Rad Runner 2
-Grin Base Runner controller
-Cycle Analyst screen
-G62 Bafang 1000w rear
-Magura MT7e brakes for safety (amazing brakes with soft feel, can use one finger)
*Adding front regen motor and phaserunner controller next.

I bought the Enorau https://eunorau-ebike.com/products/bafang-fat-bike-48v1000w-rear-hub-screw-freewheel-motor

-threaded it to the stock spokes and it works. I then installed Grin Tech baserunner (with motor adapter cable) which stutters a bit on takeoff. My wife's radwagon has the Area13 (boltonebikes.com) upgrade also found on Electrobikeworld site. The Area13 upgrade is simpler and hassle free and climbs hills better the way it delivers power. The Grin Tech controller is way more geeky and you can achieve higher top speed (28 to 29mph) using the Field Weakening option. I have a strange issue with bike stuttering at takeoff that their support can't really fix. I got it manageable and will add a 9continent or Grin All Axle front motor, so not too worried. Used Grin Tech since I will add front motor to one screen and one throttle with a 3-way toggle switch to choose which motors run on the fly.

*There is a youtube guy who inserted the above linked motor into the stock case on Rad Runner2. But the holes are not a perfect fit and some drilling required. I did not want to mess with that and risk water damage etc.. So I learned how to thread the spokes with some patience. Some others like radwagon can swap right into the shell/casing. But that is G60 to G60 Bafang style. G60 vs G62 slight difference. Pay attention to which side cable exits. Hence I got the 1000w vs the 750w. The watt rating is really saying the wiring is beefier etc. Not a real number since I push way more power (approx double the normal) into all 3 of my ebikes with no issues.

I have a Rad Runner using Grin Baserunner v4 controller. I have some serious hesitation when starting and no power if rolling backwards on start/throttle. Only when my 200 pounds of weight (or a little weight) is on the seat. Did you encounter this? Both original Rad Fat (Bafang 500w?) motor and the new Bafang 1000w hub I threaded in have same issue. Grin support is at a loss to the problem. Bolton Bikes 35amp controller works fine (Electrobike sells identical). So motors are good.

Did you make your own Motor adapter cable?  Grin made me an L1019 to Z916 (Rad motor). I sent controller, cable, original motor to them to test and they said its ok.

Tried autotune on phaserunner software, default Bafang Fat settings, Pass-thru on Cycle Analyst and Bypass feature on Cycle Analyst. Not sure how to find the right cable to plug a throttle direct into controller. I have extra throttles and one from Grin (which I tested with).

Let me know if you have some helpful advice. Trying to get rear motor working so I can add a front regen motor.

Thanks