I bought a new 2017 F150 this past year with plans to tow a travel trailer with GVWR rating of 7600 lbs. (that's just for the trailer, at max load capacity). Although an F150 with the 2.7 liter ecoboost can be had with max tow capacity of 7600 lbs (or close), so I initially thought maybe I could do with the 2.7 and the test drive was impressive with that engine for acceleration with just the truck, i.e., had way better acceleration than my old 2002 F150 with the 5.4 liter V-8.
After doing the math to figure out what I would need for Gross Combined Vehicle Weight, i.e., truck, loaded to the greatest I would ever need, and max loaded trailer (which I've later figured out I should probably never reach, but could get to within 500 lbs of it at some point down the road) I ended up getting the 3.5 ecoboost, max trailer tow package, and heavy payload package.
It gets a bit complicated and confusing figuring it all out as you need to include the trailer tongue weight in your max GVW for the truck w/ passengers, dogs, camper shell if you have one, and all the stuff you might ever want to load and take with, plus trailer tongue weight, hitch weight, etc. I actually put together a spreadsheet to tally up everything, guessing at some things but trying to guess a bit high, etc.
Anyway, had I gone without the heavy payload package, I would not have been able to carry more than one passenger with myself driving at times, and very little cargo, without a good possibility of exceeding the GCVR, or the GVWR of the truck when the tongue weight of the trailer is added. Your auto dealer may be able to help you with this, but be careful as not all will make the effort to make sure you end up with what you need for payload capacity. Good luck.