The new cold and insulation mechanic is solid. But almost too solid: I can’t leave a house without instantly cooling down. While wearing the patrol jacket (worn, low insulation), which as the name suggests should excel at patrolling. But military clothing should be suited for any outdoors activity, while also having a somewhat decent water repelling stat.
Therefore I suggest either a clothing layer system or fixed insulation and waterproofness values.
I'd suggest layers for:
Upper body
-base layer: tshirts etc.
-insulation layer: warm kit
-outer layer: your jacket/layer for camouflage
-additional layesr: rain coats etc. Or for just cuddling into a tarp. Stacking items should be possible, so that you can wear a waterproof layer (e.g. Poncho) above all clothing and backpack which is covered by a ghillie suit
-vest layer: I wouldn’t change this, it remains above all other clothing, raincoats go below it to still allow access to the vest inventory (but new top layer items like ponchos or changed ghillies could cover it too)
Head:
-base layer: wearing a beanie/bandana/other kind of soft hat
-protection layer: helmets (but the combination of helmet and soft hat only allows smaller soft hats, up to beanie size)
-tool layer: headlamp/NVG (might be possible already, idk)
Lower body:
-base/insulation layer: hypothetical long Johns
-outer layer: your pants
-additional layers: waterproof gear, camouflage
You should only be able to access the outermost layers inventory, however putting on a raincoat shouldn’t change that and just keep access to your outer layer. Changing clothes shouldn’t turn into a dressup game either, a direct change should be possible (maybe including a small timer to simulate taking higher layers off and on). Clothes stacking could be allowed on appropriate slots, so wearing 2 T-Shirts underneath a coat should be possible, similarly to a T-shirt and two coats above it. But your inventory space should not expand infinitely.
Also certain items like T-Shirts dont deserve inventory slots as there are no pockets on them