I have no idea if Flood 3.0 will be realised, but here's the thing. How about your own inventory where you could browse your cosmetics and preview yourself? Also you could change your player model and phys gun colour in there. This won't confuse some players with "how can I equip my skin?" and so on. Also it won't make "store" menu so complicated/you could only buy cosmetics in there and equip them in the menu next to it: inventory. Here's an example:
I've never have any trouble equipping items with the current interface, so I thiink this is a bit unnecessary.