I would assume your concern is tipping over side to side.
diver110 wrote:
Am I correct that COG is THE issue with regard to tipping over.
I think this is definitely the issue. Once your camper is secured on the truck bed there will be a new COG established based on the combined objects. The truck by itself will have a lower COG than the combined truck and camper.
Also, how big a deal is a 2 inch difference in COG?
This shouldnt be a big deal but how did you determine there is only a 2" difference?
I suspect a pop-up truck camper would improve to lower the COG but couldnt guess just how much. Perhaps that is what you 2" measurement is addressing. Might seem a little low as the campers may be about 20" higher or so that a collapsed pop-up.