You sound like you really really want this truck and you're trying to find any excuse to say yes.
Three truths:
1. The payload is never as much as it says in the sticker.
2. You always put more weight in the truck than you think.
3. The tongue weight is always higher than you think.
So, that 500lbs of wiggle room you think you'd be buying with this F150, is probably going to go "POOF" the second you drive off the lot with it.
Of course, you are probably grossly overloaded with your current truck anyway, so anything will be a dramatic improvement.