Rental properties: Licensing, lease agreements, or something else?

Hey everyone, I’m looking into renting out some vacation rentals by the coast. I own a house with four units—I have occupancy permits for the ground floor and the second floor. Two of those units are in the attic. They were built recently; we didn't expand the actual footprint of the building, but since they aren't officially listed in the usable square footage on the permit (even though we measured up to the roofline, which counts as usable space), I'm a bit stuck. Will this mess up the certification process? Do I need to go through the headache of applying for a new occupancy permit, dealing with condo mapping, or something similar first? Or is there an easier way—maybe just signing private rental agreements with every guest to bypass the official classification entirely? Is there any other workaround? Thanks!