Rubber bands on a trainer are a good idea; re: cartwheels - been there, done that. I figure that wing bolts would have greatly increased my down time. The thing is, the way the trainer is designed the wing sits precariously but firmly into a shallow fuselage indent on the trailing edge. During a hard landing, the rubber bands allow just enough give for the trailing edge to lift over the fuselage - popping the wing and in most cases doing little damage. Wing bolts defeat this design feature, eh? Stay with the rubber bands - even if it identifies you at the field as a wanna-be!