Brit, you are in great shape to be able to run like that!
I think I would just pack in all the supplies in one trip, and figure out a way to hang the supplies, counter-balanced, so nothing could get to it.
SEKI instructions. If you do it right, your food will be perfectly safe.
It takes time and patience to find the right tree with the ideal branch, and then getting the twine over the branch is difficult (tie a little rock in the string and throw it). I can imagine the failures occur due to not using the right branch, or tangling the rope and giving up.