@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?

The exception would be if this was already permitted for STR - short term rentals VRBO then it might be worth it based on location.If you just want to buy a home and have a unit to help cover the mortgage I would still insist on lower price point or NO HOA to help get the total mortgage down so that the other unit covers 50% of the overall payment.  

The fixer uppers are not cheap to get into and your capped on your ARV so the spreads can be thin and the permitting can be a nightmare. 

There are currently 9,000 properties listed in Lee and Collier counties and 2,000 or 22% took prices drops in the last 7 day alone.Adam -- I'm in the process of building on the Cape and for the newly permitted builds, I've noticed pricing is coming down on key building materials - roof trusses, windows/doors, shell pricing, etc.  

Egress will be required and depending on your municipality you may need rental license or permit.

In fact, Burlington permitted over 900 new housing units over the last year(that's 10% of their population)!