There seems to be a double tube in there.  I just drilled out a bit of the inner tube and it worked great!  No modification to the mirror components.

I have now installed the latches... and everything works great.

See picture.

Correct, fence parts.  6 foot for $20, caps for uhmmm, less than $3 each, glue, hardware...

As you can see above, I have edited my previous post with some info and pictures.

Ok, some information that might be helpful...

I just installed a mirror in the end of my bar without messing with having to modify the mirror.

I used a 5/8 inch drill to drill out some of the inner tube of the handlebar so the mirror could be inserted.  You do not have to drill out too much and should have no real bad affects.  The inner and outer handlebars are aluminum, thus easy to drill.

New storage and large crate for carrying stuff and groceries

Go over to the Radrunner area and see what I have done, pictures are included over there.

I am working on a design to mount a 4x4 plastic tube there.  I will make it waterproof (edit) water resistant with locking latches.

I will share the design once I get it all together and tested.

Ok, have attached pictures of what I have done, not that I am finished yet, but concept is working well.

On the under basket storage unit, I have glued shut one side, the other I will be installing two latches on two sides to latch and hold the cover on.  These latches have eye loops so I can put a lock on, should I want to.

The front square tube has a small hole drilled in the bottom for drainage.  I have a lid/cover for it as well, but no latches are planned for this one.  I plan to use it for drinks or whatever.

Now, on my wife's bike, she wants me to paint her storage tubes black....  not sure if I will or not....  I prefer function over what it looks like.

I contacted Rad and asked what voltage do they run the front and rear lights.... answer... they are both 48 volt DC lights.... so be careful on trying to tap into their wiring.

I am trying to find a good mirror for my Radrunner +.  I tried one I purchased, but it does not extend out far enough to be able to see around my arm.

Has anybody found a good option?

Since the riding position is mostly upright, one's own arm pretty much gets in the way.

Any help would be great, thanks.