Hmmm, don't give up yet. If the Northwood settled the height issue, but didn't' fit the truck, why not take a look at the Outdoors RV Black Rock?
They are built similar (sister company), 2" thick aluminum/insulated walls and this model shows a 6' 11" interior height. It's an awesome layout in a small trailer.
Black Rock 20RDIt has a "full featured" dry weight of 4,300 Lbs so your truck should handle it fine, and if it's just the two of you, well this layout still has plenty of room for the cat.:C
Last, the Black Rock series is marketed for back country/off grid camping, but most come with the power pack (roof A/C and microwave) and you also can get mountain storage (rear receiver hitch, toy lock), or add the generator pkg. These trailers also include the X4 off road system, more ground clearance, HD shocks, and greaseable shackles/pins.
Since they aren't loaded up with the luxury stuff, it keeps the weight down without sacrificing build quality and four seasons insulation which we folks in the South (also in Texas) can really benefit from in the Summer.
Here's a video for the Black Rock (I think he's had too much coffee!)
Back Country series (Black Rock)Since I'm all about construction first, watch this, then compare it to anything else you are shopping for.
Outdoors RV construction
