Always, always, always go bigger than you think you'll need for towing capacity/engine displacement. When my ex and I lived in Spokane, her folks came out to visit towing their fifth wheel (30+ footer) with an F-150. Forget which engine, but it was like the midsize truck V8. I told them that wasn't going to be nearly enough truck for the job, and they should've gotten the F-250 with the 460. Her dad just laughed it off and said it was plenty big enough.
They cracked the block just past the Montana line on their way back to Michigan. And I do mean
cracked. Had their 5th wheel towed back to Spokane to park it in my yard. Showed up a couple weeks later in an F-250. With a 460. :whistling:
This was before diesels became so common, but the rule still applies. Go big or ya might not get home!
~Boar