Hi Leeann
I have seen them but never used one. When you pull the boat out from underneath the legs it sits on don't look to be all that stable to me. Not only that there is a limited amount of space for your gear.
Most of the good camper trailers make a boat rack and some just fold off the top with gas struts when you stop for the night. There are some great little fold up trailers these days as well. I wouldn't think that the Belco would be all that great off road either.
If I were you I would be looking at a good off-road model with a boat rack on top.
Cheers
Derek