I think it's a matter of taste, Pistacia. But there is perhaps a more elegant solution?
Underpants.
How about black boxers for male characters? I think boxers would be a better choice than that whitecord grandpa undies (that aren't very fitting with those tattoo skins)
About female characters, i dunno. Maybe we'll have thousands of guys ogidling their character in wasteland lingerie, but for that, we have decent tribal rags, like those in Tactics. Or do you have any other ideas?
Anyway, i think it should be very unfitting to have no any skin protection, like getting sunburned, dehydrated...restricted? Charisma malus or telling the naked freak he should GTFO or get some clothes before he gets shot.