My final plan to avoid lists and lists of equipment is to create another category, Traveling Equipment. PCs specifically have to buy these boxes from the get-go, they don't automatically start with any, mainly due to the expense of traveling, which includes but is not limited to mounts, feed, hirelings or henchmen, food, water, and a myriad of supplies and equipment.
Each box costs a minimum of 50 gp and the GM can change that price as they see fit. The number of boxes available to each PC is only limited by their purses and how far they are going. Assume one Traveling Equipment box will supply the party for one day, so a party of four PCs and a few hirelings and henchmen, traveling for 14 days to a destination and back (28 travel days total), will need 28 boxes. That's 7 boxes for each PC at a cost of 350 gp, which is 1400 gp for the whole trip!
If the PCs choose to go lean, then they can stretch each box for two or three days but risk losing mounts, men, food and equipment along the way, or simply running out at inopportune times. I leave it to most GMs to determine those situations as appropriate.
Gaining Traveling Equipment along the way is easy, provided the GM allows that the little hamlet the PCs stopped in has the necessary supplies. This would require a successful search roll, with penalties for anything smaller than a town (village, hamlet, thorpe, etc) and bonuses for anything bigger (city, port, capital, etc). Trade caravans that are encountered should be treated as towns (for rich caravans) or smaller (for poor). Prices, of course, will depend on a variety of factors.
Gaining Traveling Equipment from defeated enemies is also possible, but are constrained as earlier presented: 1) supplies can only be gained from a mobile group's camp, not a permanent lair unless allowed by the GM, 2) the enemy camp must be specifically (and successfully) searched to find supplies, 3) there is no penalty for searching humans or demihumans camps, but a -2 penalty is levied for searching humanoid camps, and -4 penalty or more for other creatures and monsters, 4) the search takes at least 30 minutes, and 5) only one box can be recharged for that search area unless specified by the GM.
For example, Jim, Giles and Orin are traveling to a nearby dungeon and search an wandering orc camp for supplies after slaying the orcs. They get a -2 penalty for the search and successfully make the roll, finding enough equipment to fill one of Jim's Traveling Equipment boxes.
Later on the return trip, they've completely exhausted their Traveling Equipment. After killing a mendicant otyugh, they search with a -6 penalty and find nothing worth salvaging. The scene fades on a desperate situation as they have another week to go in the wilderness and no known safe havens ....