Jumpsuits?
Your should be worn underneath your jumpsuit.

It may be me being a dumbass, but it feels like being able to wear things overtop would be one of the best and most attracting traits of an armored jumpsuit. And while it being without allowance for other armors overtop makes total sense, but I think it would make much more sense for tailored clothing to be acceptable overtop, both to conceal and just for genuine style purposes IC.

I don't even mean that. I mean just, normal stock items. Can't wear a a baggy, three sizes too big pair of sweats on that skin tight leather suit? Yeah sounds normal.

Wearable over thick Items:

tie, coat, labcoat, topcoat, overcoat, longcoat, greatcoat, browncoat, trenchcoat, jacket, trench, boots, cane, umbrella, robe, blindfold, bikini, habit, muumuu, hawaiian, bolero, apron, scrubs, shawl, scarf, bathrobe, armband, necktie, obi, cummerbund, belt, duster, veil, parka and balaclava

(source BGBB, 2015)

because leather is considered a thick item because of how much @coverage it has, and it's armor (i think)

There are plenty of tailored items that your character can acquire to 'hide' armor beneath.

Someone was nice enough to post a list of them here in this thread.