Next up, I reinforced a couple of the formers up the front end of the fuse to support the 2 kilos of battery I'll be hauling around. I had some good quality 4mm ply laying around, and after making a template out of card, cut some ply.
The 4mm ply more than doubled the thickness of the original ply, and feels rock solid to support the batts. Also had to make a battery tray, which I scanned before I glued into the plane in case anyone else wants a template
It's pretty rough, but has worked out great in the final setup.