Rough calculation, not counting water tanks and other internal stuff is pretty simple.
When you have so called 8 foot camper, you have about 11 feet of the camper (including cab-over) in front of the long bed axle, when 4 feet behind it. So center of gravity is way up front.
When you have 10' camper, the front is still 11 feet, but you are going to have 6' behind the axle and not only taller rear is much heavier than cabover, but often holding tanks (read heavy) are located at very rear.
So even 2 feet might not sound like much more, but the rear axle will get good beating with it
Per my observation manufacturers don't pay attention to make center of gravity up front.
Generators, propane tanks, batteries usually are mounted in the rear.