Add Jardine’s Beyond Backpacking and Chris Townsend’s book to the list but neither offer much on resupply logistics.
Are you going the full 300miles? And out for how long? And some other questions: how heavy a pack are you willing to carry on resupply days? Do have someone willing/able to resupply you? Do you have an extra bear can you can cache yourself? Are there campgrounds with bear proof storage boxes a short distance from your main route?
Me, 10 days of food at a shot I can manage. (Though I may push that this summer). I’ve walked in, and driven in resupplies sometimes leaving them in a bear can stashed close to my main route. And I’ve left resupplies in bear proof storage boxes at trailheads and at forest service campgrounds that require 10, maybe 12 mile out and backs to retrieve.
All that said, I worked up my time. I had plenty of week long group treks then started going solo. Then add distance and days and playing with different resupply method ms to build experience and confidence.
perhaps a bit more detail on what you are thinking will help with crafting more specific advice.