Holy Moly Mike. I have an F250 (diesel) and I couldn't and wouldn't even try to carry that TC on my truck regardless of the upgrades (even though it is possible for me to do it with some serious upgrades).
I suspect with your F150, you are way over your weight limits.
IMO, if the transaction(s)/ discussion(s) were recent, I would contact both the RV dealer and the Ford dealer (write to the Dealer Principals), outline the situation and tell them it is their problem so solve, give them 5 business days to work something out between them, and state if you haven't heard from them with a solution that is satisfactory to you, then YOU are going to go to your local DOT people and get them involved.
You got very bad, misleading advice (probably just to make a sale) and you should not be the one taking the risks or paying the proce for this bad advice.