There's always going to be someone ready to say a 2500 is the obvious choice, but not everyone wants to drive around an HD truck all the time when they aren't towing. Obviously a 2500 would tow better, but there are competing concerns.
So then there are two natural questions:
1. Can you stay under your limits with the F-150? It appears you should be able to. You're certainly taking the right approach, and you have the scale slips to show you're under the limits.
2. Does the actual, honest-to-god towing experience jive with the idea that you're within limits? Sometimes people make the numbers work but don't like the towing experience. Sometimes these people have a bad hitch setups, but sometimes they don't. The only way to know is to get it out on the road.