A little reinforcement of the cabin pillars done by laminating stringers helps a good bit, as well as solid wing struts. I've been laminating wire into the fuse end of the wing struts, with a number of nicks placed on the wire for solid gluing, along with adding a bit of balsa in the fuse for the wires to glue into. I imagine it's probably more difficult for rubber flyers however, as it's not exactly as if you have control over the landings, unless the model responds to telepathy, or maybe yelling at it, etc...