I was thinking along these lines. My (partial) solution was to use a RPG with mechanically simpler PC design. For example, if I wanted to run this kind of campaign in a traditional fantasy realm, I’d probably default to using The Fantasy Trip/In the Labyrinth, with players controlling 3-5 PCs simultaneously.The main shift to make Expedition D&D (my term) work, imo, is to change the party size. If you have 4-6 heroes then dying of disease or starvation is not fun. It is too brittle: if it happens you lose based on something that is essentially tangential to the main game (dungeon crawling etc.) That means tracking supplies is not fun, nor gameable, because there are no real stakes.
I think you need to embrace having a larger party--say 10-50 people. A few of these are hero characters, some are retainers, some are porters. Overland you have big combats including the retainers. When you get to the dungeon you switch to playing just the heroes. If the heroes die you have retainers you can promote so players get to keep playing.
Not only does this flesh out the various roles (keeping them in players’ hands), but facilitates the “promotion” or addition of other characters if needed.