You Should be fine I pulled my boat behind a "81 Prowler TT" for years on one just like that 18' Nitro bass boat. Until Someone told me I couldnt that it was to much weight I welded a cross peice on after that and then sold the camper to a guy from work that did the same thing and I saw the camper last summer pull in the campground all fixed up and sparkley pulling a boat on the hitch I put on. That had been pulling boats for over 10 years. That being said be smart if it starts to bend add some bracing and weld it to the frame.