I used to take a dodge Caravan hunting...I'd take out the rear seat so I had plenty of room for a deer, then I'd line it with a HEAVY DUTY water proof tarp. I removed some of the internal trim pieces so I could tuck the tarp underneath so it would stay in place and seal up better. I also sprayed the tarp with a aerosol sealant. I could hose out the back of my van without even getting the carpet wet (run the hose in through the side door, kneel on the middle seat and spray).

A buddy of mine had an SUV back when we were in high school, he removed the rear seats, laid down a tarp, then put a kiddy pool in the back that the deer sat in. The pool caught almost everything, and the tarp caught any splatter etc that would make it out of the pool.