Or; as few things as possible.
Backpack features don’t make up the majority of a packs weight, but they do make up the overwhelming majority of the weight which is easily negotiable. There is only so much weight to be shed with material (before you sacrifice durability), only so much with suspension or frame elements (before the pack carries poorly), and for a technical backcountry pack good side pockets (and belt pockets) are mandatory. So the design task left is to make it possible to carry all the technical goods, along with the unexpected and unexpectable, with the least material possible.
This includes snow gear like skis, crampons and ice axe(s), and a shovel, along with water gear (PFD), and perhaps something odd like firewood or even a bike.
I’ve settled on an extension of the reinforcing layer of bottom fabric, with horizontal daisy chains 15 inches apart. Each daisy has a second layer of fabric inside. Not only does each bartack thus have serious resistance to the ends pulling through the fabric, but the load is transferred to the whole fabric panel, and thus 16+ inches of seam. The sleeve is not primarily intended as a pocket, being non-dimensioned, but is open at the top and thus not a bad place to stash pesky things like paddle blades, but the first intention is to both spread the load and provide abrasion resistance.
Pictured above is the full deal, for a trip which involved a 12 mile hike to even reach the skiing, and ended with steep skiing (on terrible crust) at 8500 feet. A shorty 45cm ice axe mounted, old school, to a cord loop on the lower daisy. The shovel shaft went inside the sleeve pocket. Skis mounted diagonal, with ski straps, and crampons went under the top cinch strap, on top of three days of gear.
The final piece is the top strap, which is bartacked into the middle of the top daisy chain on one end, and with the buckle directly under the upper stay pocket on the other. When the pack is on the empty side the angle of the strap, combined with the taper of the bag, provides compression. When the pack is full the strap pulls the load towards the suspension, transferring the load and enhancing stability.
And that, is it.