If you are getting the 150, like the others, I'd make sure you get the HD payload package. Mine has 2200 lbs of payload and I use it up pretty quickly. My trailer weighs around 8000 lbs every time I pull out and I use up all my GCWR of 15300 lbs, too. The truck handles it fine, however the engine needs more power to handle getting up to speed.  
Regarding the reciever rating, I had to replace mine because it failed. The square tubing began to split running  tongue weights of 1050-1150 lbs (measured). Not to mention the Ford reciever winds up like a limp noodle compared to the DrawTite unit I replaced it with. 
Had I to do it again,(and next time I will!) I'd probably opt for the 250 min, just for the receiver rating alone. You might be surprised at the tongue weight of a trailer that size. I agree with others, price them out and you might be surprised. You don't need the diesel option to pull a trailer. The 6.2 L should do fine.