truck camper mpg vs. fifth wheel

Thanks. A little help from the wife driving is part of the reasoning also. We did a 7500 mile trip out west this summer and even though my wife and daughter both pull trailers around home where we know the roads, I wasn't very comfortable with either pulling on unknown roads. We might go 100 miles on wide open roads then go through congestion where I was not comfortable with them driving. I would feel a lot better if she was just driving the truck with a camper on the back rather than pulling the 38' whale behind her.