Re: trampoline as tractor -
I'm not sure simple
chicken wire around the perimeter would keep either predators out or your bunnies in. My dogs have knocked the screen door right off the tracks, so I know they could misshape some chicken wire in a hurry. And rabbits being diggers by nature...
Almost all designs for rabbit tractors I've seen include a sturdy floor of wire, which gives better security and strength to the structure. Hope that helps!