try epoxying a fibre-glass cloth around the centre of the wings and it should be pretty much solid, and youd be surprised at how hard you can land some of these planes before they break, i managed to dead-stick my plane (came on approach too fast and overshot the strip) onto a rough, recently-ploughed field which just broke the wheels off, simple matter of epoxying them back on to the bottom of the fuselage.

MonoKote is the brand name, the plastic sheet stuff is just known as "covering".