I got this rack. Dispatch Two-Bike Rack - Swagman 68684 - Bike Racks - Camping World
It is very well made, very heavy duty, and is approved for RV use. It can also be used on the back of a car/truck. A little more expensive than some but I think it is worth it. My sister and her husband used a normal bike rack made for cars and it broke and they lost their very expensive bikes. This rack is made to take the bouncing on the back of an RV.