Is it possible to do a 'no MB expansion' run? I know Miller automatically establishes platforms etc but a bare-bones playthrough would be interesting imo.
for the most part, yeah... especially with Markers On, the game is already rather easy. so limiting your upgrades is actually pretty fun...
i'm replaying most of the Missions now purposely using the upgraded default weapons and the base M2000 hunting rifle, and it's actually a lot of fun. I'm replaying missions with my own forced Subsistence ruleset too and it's pretty cool... makes you act pretty creatively... I snuck into one outpost and I took out the guards with their own mortar barely 15 feet away, took their AKs as my first weapon.
there may be a couple missions in particular that really require certain items or upgrades (I'm mostly thinking the fulton upgrade or rocket upgrade) but even those are do-able without, and you can probably afford/unlock those in time with just a 1/4 R&D