New travel trailer Gulfstream Conquest 323tbr

Not sure where you got your weight info but it seems little high. Although factory numbers are usually low...7500/9800lbs. Either way a 3/4 ton should work for this trailer but I'd never walk away from a 1 ton if it was close in price. Good luck with your new trailer :)

Having owned two 5.4 Fords, I would avoid them, as they will struggle pulling this rig. 6.2 would be a better choice.

Had a 5.4 in my 98 Expedition. Replaced the head exhaust gaskets, both sides, TWICE. They liked to leak. Cast iron header to aluminum head. Once started leaking it would etch into the aluminum. It only had 60000 miles on it when we sold it after 16 years.
Having the 5.4 as a base model engine in a Superduty is/was the same as getting the V6 in the F150.