Great idea! When I get a replacement controller I will probably open the case and apply some sealant all around to make it waterproof, and also make some kind of enclosure to prevent water splashing on the controller.  I am thinking this particular controller was not assembled properly and that is why this happened to me so soon.

I have seen some controllers for the RadMini that is supposed to be plug-and-play for the Runner. Maybe those are better constructed, unfortunately the website lists them as Sold Out.

https://boltonebikes.com/collections/motor-controllers-and-displays/products/2019-radpower-upgrade-kit-with-tail-light

My RadRunner that I purchased in Nov '19 stopped working. It keeps blowing the 40A fuse located in the battery. I checked everything per Help articles on RadPower site but no help. Finally, I decided to take a look at the controller itself. I opened the box and found a lot of junk from moisture inside. I never ride the bike when it is wet, but I have run through small puddles if I could not avoid it. The controller is not water tight at all. There are no seals and the cover does not fit tightly so no wonder water got there. Anyway, I also found one of leads from the (large) capacitor corroded away. That is bad design! I wrote to RadPower Support to see what they have to say.
I attached a pic of the controller and the missing wire is circled.

I made this box and it works as expected. I will add a port to measure the voltage so I can properly label the switch positions based on the voltage.