RE: From yet another box of stuff in the shop comes..
MJD, I vote for something like a GLH. It'll be fast enough to be fun and a simple build. To simplify the build, make the wing nonremovable. This can also save weight [unibody].
I built something very similar years ago for a ST .15 and had to retrofit an additional spar into the sheeted foam wing.
The original design had no spar, just a little [too little] glass over balsa.
It was just 2 channels and about 27-28 ozs IIRC.