The ones that extend out and replace the tailgate, can also be mounted in reverse, so the tire is pointing in toward the cab and not out by your boat. They are real nice in my opinion, but if you need the bed room and towing at the same time, they might not be the best idea. Check these out too, they arent the cheapest, but are they are extremely nice and very well made, check out the rear carrier on the Excursion, I've seen that one up close, very nice bumpers
http://www.roadarmor.com/ra3/ford_trucks.html Theres also this vertical one
http://www.pickupspecialties.com/Tire_gate/tiregate_vertical_series.htm