Can you add a faux unit to building just for LLC and mail?

[Rick Jones]

Not sure if this is locality dependent or not but I'm purchasing a 6 unit building and I am wondering if I could add a 7th unit just to list as an address for my LLC. I would also just use this as my business address and receive rent checks and other business related mail at this address. I am not actually planning on physically adding a unit within the building. Thoughts?