I'd also make separate slots for the armor items like a "head" slot for gas masks, mirrored shades, riot helmets, etc. I'd also have two separate torso armor slots, so you could wear a bullet-proof vest under your leather jacket, but the bullet-proof vest's modifiers would only apply to torso shots. Anyway, so as to make it simple, a suit of power armor, and environment suit, or anything else contiguous like that, would just be dropped into the "outer" torso slot and it would automatically fill in all the slots it applied to, and dump anything else into the main inventory.