I know Blue Ox has base plates for late model Dodge full sized vans. Don't know about older ones, though. And there's a good chance a later model version could be made to work on an older one with a bit of ingenuity by a good shop or a creative back-yard welder. It's also likely the pick-up model would attach OK, but would probably require mods to the grille to let it poke thorough.
You said axle locks but that's a rear wheel drive and would use a driveline disconnect (axle lock usually refers to a front wheel drive). I gather he want to dolly tow with the front wheels on the dolly? If he backed onto the dolly he wouldn't need the disconnect. Best to tie down the steering wheel though, since the steering wheel lock may not be strong enough.
Former owner of 2004 American Tradition and several other RVs
Home is West Palm Beach, FL