To make it confusing different brands measure COG differently. Most measure from the front of the camper back. Lance for one measures from the back of the truck bed forward. Most pick-ups have a CA (cab to axle) legth of 54 inches. Cab and chassis trucks have a 60 inch CA. So, a camper with a COG of 54 or less if measured from the front will have the COG right over the rear axle.
Raising the floor gets you more floor space but a taller more top heavy camper. It also increases the ceiling height in the bed area and reduces the step height to get in the bed.