Baja Man,
I have a custom overlap welded extension that was custom made by an RV Lance dealer so I could tow my boat with the camper on. He asked what type of boat I had, as tongue and tow ratings are reduced with the extension.
Originally the Dodge was Class III but I upgraded to Class IV when I towed horse trailers without the camper a few years ago.
The first tube goes in the truck receiver and the other piece is welded onto that piece with quite an overlap and just clears the rear bumper of the camper. My hitch then plugs into this end with the proper drop to tow level. Test your tongue weight of the boat.( My 18 foot bow rider is under 100 lbs). A simple wiring extension is used. I do reinforce the connection with taught safety chains and inspect before each use. Been using for 24 years and stored in a dry garage.
A bonus of the extension is I usually remove the camper at the camp site and leave the extension on the truck when launching, which allows no rear wheel submersion on even shallow entry ramps.
