I agree with you, the F150 and F250 are totally different beasts.
My dad has an F350 with the 6.7L PSD and that truck is a tank. His payload is 3550lbs and he tows a 5th wheel. It is night and day difference between his truck and mine.
Repercussions....I don't know. I'm not into fear mongering, but I guess technically it could effect
1. Warranty on your truck --- only if Ford could prove you overloaded it and it caused your issue.
2. Insurance coverage --- would insurance deny payment of a claim if something happened and they saw you were overloaded?? I'm guessing insurance companies would look for any reason to get out of payment, especially liability.
Again, I just want to give you all the info you might want before making a $40k or more investment in a new trailer, just to find out you need to buy a new truck to make it "legal".
If that does happen....can I buy your F250...LOL :)