Help me do this right! (Plan B)

If you are purchasing an F150, you will be limited in weight to under 8000 lbs for reasonable towing that you will be happy about and comfortable on hills.. I have a 2013 Expedition ( same chassis and engine selection of F150) with a 5.4 L V8. I bought a 2014 Keystone Bullet Ultralight 285RLS which is 30 ft long with 1 deep 11 ft long slide. We love the layout since just 2 of us so we have the rear living 2 easy chairs in the back where a bunkroom could go if you plan on having the kids with you a lot ( different model #). The TT weighs 6000 lbs empty with a 600 lb hitch weight, tows beautifully with the Expedition and an E2 Equalizer WD hitch. We have not had a single issue with our Bullet in 2 years and every post I have seen on this site is positive about Bullets! They come with a thermal package which has heat from the furnace ducted to the water tanks, higher level insulation, sealed underbelly. The Bullet may be an ultralight but has upgraded amenities and interior from the Keystone Passport which is also an Ultralight. You could probably go 1 size bigger than we did but I know from experience this model we have is a good match for your chassis and power assuming you have the bigger engine or the new 5.0L. Good luck!