I think hallmark measures cab back
My Lance, the consumer info sheet says point that contacts rear end of truck bed forward
No standard
Anyway I would suggest you name some of the places your thinking of going in CA and maybe you can get some hands on info about camper on or off
I had a pop-ups Outfitter and Northstar on a SRW Dodge diesel 4x4 and also had at the same time a Okanagan on Dodge DRW diesel 4x4 , it was nice to take one to the boonies and one on the long road . But if your driving across the country to get to Ca I`d pick the one that suits that best