Home Depot is your friend when it comes to equipment rental. I don't know what their truck rental options are (they have them, I just don't know their rates), but I've rented a 40ft ladder, a hand truck, a tiller, a dirt compactor, and probably several other things from them. They do 4hr and 24hr rentals. Heck, I've even walked around their rental department for the fun of it, and tried to come up with reasons to rent stuff (mmmmmm powertools...).
But I've been that friend with the pickup many many times, and before that, I was that friend with a minivan. I had a Plymouth Voyager (Dodge Caravan), and it had two removable bench seats in the back. I fit a single-size mattress back there when I was a traveler (i.e., bum) a bunch of years back. Many minivans have completely removable seating, especially the older models. So, before you spend money on a rental, think about what your friends drive again.