This is an interesting thought. I was just comparing the payload of a F-350 SRW with a GVWR of 10,000 lbs in gas and diesel. The 6.8L gas has a payload of 4000 lbs and the 6L diesel 3500 lbs both in a crew cab. Are you saying the 500 lb difference is meaningless because of weight distribution? If so for someone like me who never even owned a truck this is a big revelation.
The payload sticker isn't used for any legal weight purpose as far as how much load can a truck safely/legally carry/stop or start.
looking at fleet Ford specs for a 250 or 350 srw there is only around 4 lb up to 175 lbs difference in a gas vs diesel in the same exact trucks unloaded rear axle weight.
F350 srw has 13 different gvwr ranging from 10000 lb up to 11500 lbs. Ford doesn't and isn't about to mfg 13 different truck frames/trannies/front and rear axles/etc for each gvwr.
fleet ford clicky
click on vehicle specifications.
Spend a afternoon looking at all Fords mechanical specs for the F250 and F350 SRW trucks. Then you too will see how silly those gvwr based payload sticker numbers can be in most cases.