jujube
SF VIP
Install a receiver hitch on your rear bumper of the 5th wheel. You can get a metal platform that extends the carrying capacity & is removable when not in use. Put a plywood bed wide enough to accomodate the 3 wheeled trikes. Doesn't add a lot of weight. Easy peasy, build it so the rear lights & plate are visible. Usable for many things.
View attachment 51952
Back when we rode bikes, we took them with us on our first cross-country trip out, hanging on a bike rack that attached to the ladder on the back of our fifth wheel. It was the proper rack, rated for three bikes, and what it did was "bow" the ladder out. Afraid that it was going to detach the ladder, we had to put one in the "basement" and one in the fiver when we moved, which unfortunately that summer was every few days.