Proteous,
IMHO, you did quite well overall. Slowing to 50 mph on the steeper interstate grade with a motor of you specs is frankly, probably pretty normal. Even if you would have had something.g more aerodynamic, like an Airstream, you probably would not have been going that much faster. If at all, as you probably did what a lot of us do, when we realize we can not hold 60, 50 or what ever speed on a grade except by being something close to realize, we slow down to an rpm that is high enough to keep our speed up, yet have some cushion if we need to accelerate some. I'm going to swag your motor is simaler to the diesel in the sprinter I drive. Upper 2000 to low 3000 pulling a steeper hill, no issues if I can not he the gear above it.
BUT, as you say, a lower trailer, more aerodynamic etc would probably been more fun per say, I feel you could continue renting this trailer for a trip like this for years to come and not hurt your rig.
Marty
