2015 F150 with the 3.5 ecoboost, had it since new. Medium cab (suicide doors, not a full crew cab) and 6.5 bed with ATC Cougar (7' wide by 8' long, sits on the tailgate with the gate down). Running at around 67 mph without camper I get around 20-22 mpg, with the camper on, drops to 15-16 mpg. Plenty of power for whatever one would want to do with it - I would even consider going to the 2.7 ecoboost and probably still have sufficient power. Just over 100k on it so far, and no major issues. This has been a comfortable truck for us.
Also, I have the large fuel tank (36 gallons), which gives plenty of range with or without the camper. Well worth looking for one that has the big tank, in my opinion.