Thank you all that responded! The camper has 75 gallons of fresh water, not 81 gallons. We haven't filled it due to the weight. We stealth camped coming across country and was amazed at how well the camper handled. We were running 80 lbs in the air bags and the Stableloads (I think) took a lot of sway out of the truck. We drove at between 62-65 mph and averaged between 9.5 mpg (through the Rockies) to 11.5 mpg (through Kansas and most of I-70.) Our truck is an 06 Ford CC Dually 4X4 6.0 Diesel (88K mileage) and runs like a clock.
We couldn't be happier with our set up and look to meeting and comparing notes with other TC users. Happy trails to you all and Thanks for making this this a great site!