MGSlynch, I was told by FWC (2 years ago at Expo West) that internal bed tie-downs won't work on my ZR2 5 ft bed because it's a diesel. To accommodate the DEF filler tube, there is an area of the truck bed that slopes in on the driver's side front, and the attachment point for the camper has no where to go. External tie downs are possible if you fabricate something to strengthen and attach to the rock sliders. I wouldn't attach directly to them without some reinforcement though. You should be able to find a way to go with the internal turnbuckles with a Gas ZR2.
The other thing is that the truck bed depth is too deep for a FWC so you will need a platform to raise it a couple of inches.
Of course where there is a will there is a way. It just amazes me that to this day FWC won't modify their design to work with the newer Colorado's.