Think of all the time you'd save not stopping to refuel! :)

You think hitting that immovable object hurts then the trailer comes up and hits you in the ask me no more questions even if you try. Yeah Safety is a good thing. Reminds me of New Years Eve last year coming up a hill and turning into a side street . . . in the snow and ice . . . couldn't stop . . . couldn't turn . . . heading for the corner of a stone wall . . . finally stopped 2 feet from it and had to back up to make the turn.

Tell them to give you the diesel. I don't know the towing capacities off hand but 7000LB seems like on the high end for an F150.

I've got a 7x14 tandem axle box trailer myself. My previous towing vehicle was a GMC Yukon. When fully loaded (8000+lb) I averaged 9-10 MPG and had absolutely no power to climb hills. I recently picked up a GMC 3500 1ton Diesel Van. Not only does it pull the fully loaded trailer like a dream but I averaged 16.5mpg on my last 400mi round trip. Normally I average 17.5-18.5mpg unloaded in that van.