The CG of any given camper is specified by the camper manufacturer at the time it left the factory. Dealer add-ons will change the CG, either forward or aft. Generally adding AC is located on or near the CG. I have a Travel Lite 840SBRX with a CG of 37.5" measure from the front of the bed.
My Dodge truck manual specifies a CG from 25" to 75" measured from the rear of the bed. The above TC places the factory CG at 38.5" from the rear. Well within the truck specs. However, that places the CG about 1" to the rear of my rear axle. Not really a problem because now we have to load it. Putting more weight in the front than the rear will pull the overall CG forward.
Caution must be taken not only with loading up the initial loads, but be aware of the transfer of fluids from the front to the rear as you fill grey water and blackwater while lightening the load on the front because of the fresh water being used.
with my fresh water tank empty and my grey & blackwater tanks full, my CG mover rearward 12", still 2" in front of Dodge minimum but it does get a little light on the front end so empty those tanks as soon as possible.
Through experience, storing food, clothes, generator, misc. as far forward as you can get it, the CG will only move about 8" front to rear of the rear axle. Each camper is different because of closets, cabinets, etc. so you will just have to experiment to find your best average.