Could one not use a bi-walled inflatable, then pump some media into the walls for rigidity and resistance to debris? I imagine some sort of aerated semi-flexible cement like material could fill the walls and prevent catastrophe if the outer shell were to be ruptured. My bikes tire inner-tube is filled with a hole-patching fluid, so the marketing material says so it doesn't seem unrealistic to have some sort of liquid in there too that clots and scabs when the gas in the tube starts to exit as well