Well I had a bit of time, between thunderstorms, to eyeball how I'd put an electronics mounting board in the old frame.
The new JAG5 frame has its rods on the inside of the frame rings. This allows for an electronics board to have enough clearance to be directly mounted on the back of the frame rods. The older design had the frame rods on the outside of the rings, so there isn't much space between the skins and frame rods.
So I had an idea. A few years ago, I picked up some Stanley L brackets and figured I would find a use for them someday. My idea is to attach them to the G-10/FR-4 board, then attach those to the bottom side of the top frame ring.
I'll have to do a test fit and wrap the rear skins around to really check for clearance. It looks like the trusty masking tape comes out tomorrow!
And I'll also have to determine some way to secure the board on the bottom. I'm thinking something as simple as drilling & tapping a hole in the frame rods and using some scrap metal. But again, just eyeballing and thinking out loud. Hopefully my readers can offer some advice!