Splitting a large single tenant building on downtown main street?

[Ryan Standage]

My family has a large (7500 sq ft) retail building on a small hometown type main street. The main street is mostly full of smaller boutique type retailers. We feel we can get much more rent per sq ft if we were to split the building into 3 or 4 smaller units. 

We are thinking one main entrance that would lead into a long hallway that would extend all the way to the back of the building, this would allow access to all 4 units. Would probably keep one meter and include utilities in the rent. But how would we insure each unit had it own mailing address? Would we need to file something with the post office?

Would we need to get permits from the city to make this a multi tenant property? I've reach out to them but no one has gotten back to me yet.