In your situation and for most people I would recommend a long bed truck. You will have more choices in terms of camper models and more storage inside the camper and have an easier time finding models with 2 batteries. Also likely to have larger holding tanks.
I found out as well that with short bed trucks it is much more difficult to find aftermarket gas tanks to increase the trucks range which helps with routing and worrying less about going out into the boondocks.
A gas engine with 4.10 gears and 5 or 6 speed automatic transmission will provide good fuel economy, relatively speaking, and good acceleration for getting onto a freeway or going up long mountain grades.
Something to look into as well is the differences in factory supplied hitches if you need to tow. Many of the heavy duty trucks can tow up to 13,000 lbs. without the need for a special weight distributing hitch.
A super cab as with Ford or extended cab with the GM trucks is very handy for storing items you want to be able to get to quickly and easily while driving and not need to stop and put down the steps and get into the camper. We use the rear space for a small 12v plugin cooler, jackets, photo gear, firewood, shovel, axe, fishing rods, etc. that we want to have readily available or don't want to put inside the camper. The crew cabs add an additiona 18 to 24 inches in truck length and similarly increase the distance between the axles and the truck's turning radius.
The 4.10 gears are important to get the most out of the gas V-8. It needs a lot of RPM's to produce maximum torque and low gearing helps a great deal.