there are a couple of a small trailers that attaches to the back of the 5th wheel that are designed to carry small scooters and/or golf carts. Swivel Wheel is one such trailer. There are also electric lifts that attach to the frame to carry a small scooter on the back end of the trailer.
The main problem with any of these is that they are almost guarenteed to void your frame warrenty. Some folks have waited until the warrenty period was up before attaching something like this, others have said the heck with the warrenty and added the accessory any way. Just something you'll have to decide.
If you google motorcycle carriers you should find several different models and types to look at. Good Luck.