My 2 cents.... if ya gotta drive the truck everyday, then some major compromises and careful attention to weight can allow you a pretty well equipped rig for truck camping, yet maintain good fuel economy. Hadley has done a very thorough job of detailing that here. For a family of 4, unless all-ya'll really spend a lot of time outside, cooking, pottying etc., you're going to be cramped. Especially if you are not tiny people. It's also really tough to stay under maximum payload...most people don't. Air bags, extra springs, and other add ons can keep you on the road, but I feel that you'd be safer and happier with more truck. Bigger brakes, bigger cab, more room for a real toilet/shower, trailer towing capacity, better weight distribution and more latitude towing.... that's what you get with a full size truck...the trade off more gas and harder to park. My stock truck gets 10 or 12 loaded, less in the mountains, more if I drive slower.