We did West TN to Durango, CO this June and our F150, 5.4 with factory tow did a fine job. Our trailer is 26' box. I can't imaging towing 34' with an F-150, but I'm far from an expert.
Agree on friendly campers and also agree on most of Europe taking vacations at once....we had the Scandinavians in June. Never have seen real grass in West TX or other you mentioned....think rock/gravel is their substitute. Also agree that most wifi sucks.....HATE Tengonet! That's why we added hot spots to our cell phones and love it.
Extras not noted - probably since you didn't go through these areas....allow an extra day for wind in the Amarillo area. 40mph+ gusts cost us a day that we'd planned on spending in CO. "It blows like this ALL the time"!
Allow a couple of hours to hop off I-40 and onto old Route 66 at various places....nostalgia. Some very cool places. We did not get to the Route 66 Museum but had planned to.
Plan to drive 300 - 350 miles a day - not more. It's the journey, not arriving 30 minutes earlier. Take your time. Enjoy.