Travel from south Texas to Belize in RV w/enclosed trailer

I think I posted this in the wrong place, so here it is again.

Hi all, Planning to caravan from southern Texas to Belize sometime in the next year or two. I will have a 42ft rv with a 22 ft enclosed trailer. The trailer will have my stand up tool box, golf cart and my street legal car. Does any one have info on the boarder crossing permits for this big a rig? The online info is all about cars. Not rv's. any help and info on this such as route and travel suggestions appriciated.
Thanks'
Doc Page

hi, steve breitweiser here, have goood friends in brownsvill, , sounds like a great trip, i have a 27' rv and almost every tool needed for servival [ i.e. metal working equipment ], , don't see any real problems with good planing, choosing best route and armed security, big nosey dog, good training of ALL PERSONS,  LUCK ALWAYS FAVORS THE PROPERLY PREPAIRED ,,,can be great fun,,,  LETS TALK. 773-392-1163