To update, CG is even less a factor than I described. CG is a factor when the turning moment is centered around a perpendicular or lateral line...an airplane wing for example. None of the weight is born elsewhere. With a camper, the weight is borne reasonably equally over the bed of the truck. Wiht a rear CG, perhaps 10% is borne aft of the rear axle. Presuming equal psi on the truck bed (probably pessimistic because the cabover section is supported by the front half), only the portion further away from the rear axle than the front of the bed is any actor. This probably means only the weight on the tailgate is a consideration.
I have a farm, and frequently put 1000 pounds on my tailgate with no problems. I cannot see how CG is even a small factor in stability.
What makes the front "light" is simply depressing the rear springs. That causes weight to be taken off the front. That is why equalizer hitches work with trailers. I also have a trailer with 700 lb. tongue weight.
Use airbags if necessary, keep the weight at something yoiur truck can haul, and you will be fine. CG is a factor only if it falls over an unsupported part of the truck. Unless you are hauling a crane that will never happen.

By the way, working trucks frequently haul well above the rated load. Those ratings have a significant safety factor built in. One seldom hears of structural failure....however, you might be that one.

By the way, I have a degree in engineering. This isn't all guesswork .

The issue of CG is misleading. The real issue is one of moment...the distance from the CG to the rear axle times weight. Thus 2000 pounds at 6 inches has the same effect on the weight on front as 200 pounds at 5 feet. Thus, if 200 pound tongue weight of a bumper pull has no effect on steering, neither will a CG of a camper six inches behind the rear axle. Your measurements will vary, but the principle remains the same. A small shift in CG is very unlikely to destablize the vehicle.