The problem with stiffening the rear leaves is that the truck will ride harsher, and have no flex....and, it must add height unless you only add overload springs that it hits on the way down during compression.

The AAL only adds 1.5" of height, so garage issues will not be the problem...making the front match vs driving around with your butt 1.5" higher than the front than normal is more of an issue.

Since it sounds as though you vary between running empty and overloaded, the most elegant solution would be helper air bags.

These add no height per se, as you inflate them when needed, and they augment the support of the leaf packs, preventing sag.

You install a small air compressor, 2 bags, and adjust the height/support from the drivers seat, pumping it up for loads of drunken friends, and pumping/drainging it down for loads of empty passenger seats, etc.

You can also save $ by just getting the version you pump/bleed at a gas station/home etc....as needed.

I believe some XOC have also installaed air shocks for the same purpose...although I don't know them or their set-ups personnally.

So - to avoid porn star pose driving when empty...you can do:

Thicker overload springs
Air Bags
Air Shocks