Design Thoughts

It might be a simple thing to try our an old design for the cardboard trainer from the 80s, in foamboard.  There were two versions of the aircraft, the high wing trainer called the Apprentice 60, and the low wing machine that used the same wing, the Craftsman 60.   Both flew well, designed for 40 size IC engines, but would fly on a variety of other sizes.  One Apprentice 60 flew on the 21 size four stroke rotating head valve engine, others had engines up to 90 size (15cc)  The design was based on corrugated cardboard, from memory B flute craft paper both sides.   I was 60" span.    Back then electric power was not feasible.    Unfortunately the original die cutting tooling is no longer available.      See https://photos.app.goo.gl/RUEtSc5hF9jAVcD98

Phoebe in the latest RCM&E looks like a very suitable candidate, designed to be made from, mainly, Depron with a Kline Fogelman airfoil.