Purchasing First RV- would like some advice...

“so Also, we will be using a 2016 Ford F-150 V6 4X4 Lariat as our vehicle (11,500 tow cap).”
What’s the truck’s payload? Probably be enough but PL is a better number for towing capacity after you subtract all the stuff and people in the truck.

“says the salesman” Disregard all the salesperson says.

As WanderingBob says, two doors are not necessary IMO, and takes lots of space.