I'm planning to throw a converted Ryobi 32CC engine on there, so the weight will surely be an issue. My brother is a machinist, so maybe I'll try to work something out on the cheap through him.

Since you've built one of these, perhaps you can answer this: If I build the plane with fixed gear initially, would it be difficult to come back later and add some sort of retract mechanism after a few flights? (Assuming I can keep the plane intact that long of course.)