Thanks for all the replies everybody, and the good advice. Can't wait to see DH's face when I tell him "put the seats down honey, we're going to get goats!" Gotta get a Barn Truck. Gotta get a Barn!!
We have a mid-size pick-up with a canopy and a rubber mat in the bed. I love the mat because they don't slide around despite my DH's driving. I put shavings and/or straw down over the mat.