We’re now shipping rear fuselages with triangular gussets and a truss structure across the bottom of the fuselage.
The prior version had an aluminum skin, which we are no longer doing.
We include enough aluminum angle material in our kits (along with precut gussets) to make a truss structure across the top of the fuselage as well. That part is up to you: just match the bottom truss structure.
Alternatively, I’ve flown a test aircraft without the truss structure on the top and bottom: just with medium weight fabric covering the fuselage. I put the fabric on a 45 degree bias to the fuselage. Worked great.
See the separate walk around videos on youtube: