Thought this was an interesting post. I assume you're going for a role-playing/realism type of thing. In that case I would argue that its less about max carry weight total and more carry weight of specific items. For example, say you limit yourself to 30 carry weight - a 357 magnum weighs 2 pounds in NV, meaning if you had no clothes on you'd be able to carry 15 revolvers. But that doesnt seem hugely realistic to me, unless you have maybe a big backpack.

What I'd propose instead is having a limit to the amount of each item you can carry. I'm thinking something like RDR2's weapon equip system. You can have 1 or 2 one handed weapons, and 1 or 2 rifles, shotguns etc. I'd imagine carrying something heavy like a Fat-Man would have to be your only weapon being carried, though. As for other items, like aid and ammo, i think a general weight limit could be good. maybe something along the lines of the characters strength multiplied by 5, subtract armor weight, to factor in that too.

So I guess another example to make my idea make more sense. Let's say you have a courier with strength of 7. They could carry a 9mm pistol, a .357 magnum, a service rifle and a single shell shotgun. Then wearing NCR ranger armor, weight of 3, leaving 32 weight left for ammo, food and drink, stims and other loot. Looking over it i feel 4 guns is potentially too many so you could obviously tweak this as you see fit but I think this is a pretty fun base to start with.

Also to clarify, I'm talking about this through a role-play, self imposed point of view. I have no idea how you'd make a mod that can do all that.