I still say even trying to do RC is just going to discurage them. It's tough enough flying a well designed and properly setup ARF in a circle 10 or 12 times and landing successfully as a beginner. It will be nearly impossible with an amateur design for which no setup info exists, even if an expert pilot is at the controls.

A possible approach is to go the glider or rubber band plane route, and offer some design choices. 3-4 different fuselages, tail designs, props, and wing designs give them plenty to experiment with and learn from. Everyone's plane will turn out differently and will perform differently. The important thing is they will all be using proven designs that will work, so all of them will fly at least a little bit.