I've always looked at COG as an adjustable item, depending on how you load your outfit. I totally discount any COG that any manufacturer lists simply because it's adjustable (by how you load your outfit). Now, I'm talking about horizontal COG, not vertical COG. Vertical is another story entirely.
Vertical COG can adversely impact overall handling, especially with heavy items up high (microwave, high mount fridge, big solar array on the roof, storage lockers on the roof, even appliances installed in slides, it all raises the vertical COG and impacts handling.
I look at horizontal COG as a lever. If it's behind the drive axle when the TC is empty, you need to artificially move it forward by intellegent loading because that 'lever' is bearing down on the rear axle and imparting it's load to not only the tires, but the suspension, rear differential, bearings and everything associated with the rear driveline.
Kind of reminds me of my friends observation while in Alaska of the dually pickup's with their headlights pointing skyward and their tails dragging on the road. A bit of intellegent loading could have helped alleviate that and kept those headlights on the road instead of in the trees....