Converting master bedroom into separate AirBnB rental. Air
I'm originally from a small town in Pennsylvania. In that area people would frequently convert houses into several distinct apartments and rent them out separately. The area was so rural that no one needed permits or anything to do this, they just made then renovations, added letters to the mailing addresses example 123 Main St A, 123 Main St B, etc) and they were done.
I am interested in buying a house with a master bedroom (which has its own bathroom) and then having a separate entrance added to that bedroom. I would then seal off the door between that bedroom and the rest of the house making it into a separate apartment that I can use to generate income. Am I correct in assuming that the permits involves in doing this in a major city like Tampa or St Pete would be costly, might not even get approved, and would likely increase my tax burden? Could I circumvent some of the cost by not giving the new apartment a separate mailing address and only renting the new separate apartment out in AirBnB so it doesn't need a mailing address?
Any thoughts or opinions? Is this a generally bad idea for any reason I haven't mentioned?