The owner was living in the basement & it was completed without permits. 

Mixed usages, such as a furnished mid term rental of one unit or vacation rental usage (where permitted) is also an excellent way to boost revenue.

You can specify blackout dates when the property is not available for rent if you wish to use it personally during certain times of the year.Legal and Regulatory Compliance: The management firm will ensure that the property complies with local laws and regulations concerning rental properties, including obtaining any necessary permits and adhering to zoning laws.Maintenance and Repairs: Property management firms often take care of routine maintenance and emergency repairs, ensuring the property is well-maintained and ready for tenants or guests.This arrangement allows you to enjoy your second home for part of the year and generate rental income when you're not using it, with minimal effort on your part.

Part of the requirements to pull a permit.

Well besides the hard costs (construction, materials) and soft costs (permitting, architecture, fees, engineering) people often forget holding costs. 

@Carlos Quiros  First make sure it is an apples to apples comparison, same scope of work, permit pulling, same quality finishes. 

I am looking for a simple design to get it done quick with a permit.

I am particularly interested in purchasing my first investment property as a short-term rental (STR).After analyzing recent data from AirDNA, I have identified several promising areas: Douglas, Saugatuck, Fennville, and I am also exploring opportunities around Stevensville and New Buffalo.I understand that regulations around STRs vary widely, and I've taken the time to study city maps to identify areas where they are still permitted.

The easiest way would be to look up the permit history for the new construction. 

What do I need to do in terms of remodeling and permits?