I should also mention something in the 2nd picture that might cause some people to wonder.

The blue block of stuff down under the rods is 3/4" thick insulating foam. To get the CG back where I wanted it, the battery pack could be placed where that blue foam is. So I cut a few pieces of the stuff to make a battery box back there. It's quick and clean. It's light as a feather and very strong. The piece you see is the top of the box so to speak. All 3 pieces were glued in with Canopy Glue. Canopy Glue is pretty useful stuff. If I ever need to pull that battery, the top is an inteference fit with just a little glue to hold, so can be pulled out. It'll be ruined but so what. The stuff is plentiful and cheap. And cutting it to fit is so quick and easy, it's not worth worrying about.

And you can do things like this with it: