D-mac,
You mention the "air-dam" effect of the long overhead (long cabover). You are correct to be concerned. Although the real concern is cabover flex and degradation to structural integrity over time.
The long cabover is a result of a "north-south" bed. The north south bed is more comfortable and convenient than the shorter cabover with an east-west bed. Personally, I will not ever own another north-south bed.
The good news for you is that you have enough truck. Even though all campers are considerably heavier than their advertised sticker weights, you truck with handle a pop-up or S-M-A-L-L hardside.
Four Wheel Camper makes a great rig. We had one. However, if you are are camping with your DW or significant other, you will eventually want a bath room / toilet.
You should seriously the Northstar 800 or 850, or a Pastime Camper (Mt. Angel, Oregon), or a Hallmark or Outfitter. I think you can still get an east-west bed from all of those manufacturers. It looks like you are in CO. Hallmark and Outfitter are just north of Denver.