RE: Designing a plane just for the wind
Make it large. Make it with 1.5 to 1 power to weight. I like an 80 inch profile such as OMP Edge. I've also had an old Morris Hobbies Giant Su-Do-Khoi (another 80 inch profile). I run a Moki 2.10 2-cycle glow engine on this class of plane. About 12 pounds all up weight.