What's the longest/heaviest you would tow with a 1/2 ton?

I didn't have issues with my 5.3 V8 Avy or my 3.5 EB F150 in the mountains. I loved my 3.5 EB, but the new aluminum bodies and 10 speeds don't impress me at all. Every manufacturer has to embellish on their product vs the competition in some way. I only know it felt great driving it. 400hp and 413tq will more than do the job. The standard in the others are base model V6's.
The other issue with the F150 XLTs is they come with halogen headlamps.
Edit: Nissan specs 7300 GVWR 200A alternator 3.69 rear end gears