Does anyone really think gearing, tire size, etc. don't matter?
Lot's of talk about lugging, "frontal area," etc. but none of that is accurate. Just because you're in 8th gear or at a lower RPM, doesn't mean you're lugging the engine. That's not what that means.
Also, the aerodynamics of the trailer are what matter, not the "frontal area." The design of the trailer matters more than the area of the front end. Our new camper is much, much worse on fuel economy than our old one, and it's a lot smaller.