We recently upgraded to a Freightliner from a Dodge 1 ton. The Dodge would get 16 mpg on the highway without the trailer and 11 with our BC. The truck would pull strong all day long. The FL has a Cat C9, larger motor than usually found in these trucks and has air brakes. Going to have our Trailer Saver installed, 1100 mile trip, we averaged 10.8 mpg without the trailer. We have only pulled the trailer for short distances so will not know until our upcoming trip to Colorado in Sept, what type of mileage we will get with the trailer in tow.
I guess I have "more money than sense" because I wish I had done this years ago. The main reasons for driving the larger truck are: 1) Safety, 2) Comfort and SAFETY! These trucks will stop with the trailer unlike any pickup. I know they all have great ratings on paper, but in my opinion, you don't drive paper. There are way too many overloaded trucks on the roads today and for me, it feels a lot safer sitting on top of 15k of truck that was built to move and stop the weight I am pulling.
So again, for us, the extra hassle of parking, and fuel costs are worth it. It is a great way to travel, but it is not for everyone. Whatever you are driving..........Travel Smart & Safe!! Oh, and one other thing....... Make sure you hit a CAT Scale and use the 5th Wheel Street programs to find out what you really weigh!