How bout 3 fat Chicks

??? They can usually be found at lunchtime grazing around Mcdonalds. I figure the 3 of them would weigh nearly 600-800 lbs, and if they were to fall over they are soft enough that they won't dent the back of your bed. Just have a supply of cheese burgers to toss in the back while driving and they should stay put, happily chowing as the 3 of them chew the fat. LOL