I think the best way to implement the customisation system would be to add a "Don't Starve Together" kind of system.
If you're unfamiliar with this system, it's pretty much you play the game as you do but every now and then a little present symbol appears in the top left corner of your screen. When you click on it it unlocks a a new piece of vanity for you to equip across all your saves.
If you changed the way it works a little so instead of just randomly getting them you could find suits on like other planets in crashed ships or something that would be perfect because this would pr