I want to be... a filthy rich merchant! With so much money that I could hire guards to clear out dungeons, a sword and board, a two hander to chop heads off, a thief for advance scouting and a multi purpose mage to round the group up while I stay waaaaay back looting stuff and occasionally backing the mage up throwing healing/buff magic once a while.... but I can't since there's a one companion limit... I'm is sad puppy

Pull the arrow out of your knee, AND BE A GODDAMM ADVENTURER AGAIN!!!!

How is this a missing class?

Problem: I want to be a merchant.

Solution: Get Speech up.

Speech doesn't really make you a merchant....well by definition it does. While I don't think this is a missing class and the companion idea you have is somewhat whimsical, I think the idea of being able to purchase a shop and unload all your treasure there and sell it for a discounted price that sold randomly over time would be a very cool feature.