From the cottage industry pack makers, there is the whole spectrum of carried weight vs. pack weight products. From the large corporate manufacturers, they will build what their market will buy. Has the OP looked at Z Packs, Six Moon Designs, Mountain Laurel Designs, Gossamer Gear, and ULA products? As Oregon Mouse suggested, ULA has some real load carriers for desert hikers hauling water, while the others have slightly lighter packs for lighter loads.

Most of them will build to suit, especially if you just want fewer add-ons, instead of more. One could also just cut off extra pockets if the pack was purchased used at a good price.