You haven't said anything about the tow vehicle, so a newer, bigger fifth wheel is more likely to push the limits of the tow vehicle than a TT will. However, if that is not a problem, I would suggest a fifth wheel toy hauler. Much easier to load the bikes into that than into the back of the truck bed. Plus when the bikes are out, you have more usable living area vs an empty truck bed. But the primary reason for recommending a fifth wheel is the easier hookup, towing stability and shorter overall length.
