You’re actually correct in part of your original statement Kayteg, as in the rear over hang of the truck body/bed is slightly different on different trucks. I apologize. It’s also the same on some.
However the difference in wheelbase between short and long bed trucks, cab to axle and axle to end of frame is generally the difference in bed length of the truck. The rear axle of a short bed truck is not set further “back” proportionally compared to a long bed.
And the difference of a couple inches of “overhang” of the truck bed and bumper doesn’t do squat for center of gravity. Talking less than 100lb ft of moment.
BUT, the significantly larger distance from back of cab to rear axle on a long bed can or will help more significantly in allowing the CoG of a given load to be moved forward putting more of the load on the front axle.
Thus the statement that a short bed truck helps with CoG compared to a longbed is still false. Not debatable. If you shove the same camper in a short and long bed truck, all the way forward to the front of the bed, the long bed will see more load on the front and less onthe rear compared to a short bed 100% of the time.
Point of my original post was just like others, your statement that a short bed helps with pushing center of gravity forward is misleading and false. Whether the rear over hang is the same or not.
Maybe a bit more than 2nd grade level understanding though....(to use your words)