You should take a look at your packs. Rucsack design has moved on a lot since the ALICE packs came out in the early 70s. A pack that deep, is carrying gear a long way from your back. That is leverage working against you.
If you know where you are bugging out to: you could dump stuff (food and water are cheap) then you only need enough to get to it. You can dump a few days food and water at every point of the compass for very little. In fact nothing. You use the food as you rotate it.
qjs