http://www.youtube.com/watch?v=rwD-9JKXdzA
Generally kayaks under 12' long are recommended for the patented RV Kayak Racks. They are lighter and easier to load. Some people do use the racks with 12' long kayaks but you have more overhead concerns. The FMCA magazine has a new product release article in the March 2014 upcoming magazine.
Go to www.rvkayakracks.com for more information.