The city gave me 3 options: 1) return the unit to a garage, 2) get an architect or draftsman to draw up the building plans and then pull permits, or 3) get a structural engineer to "stamp" it and say that it's up to code.

You also are welcome to do your own plumbing, taxes, legal work, electrical work, landscaping, etc. 

More power to you if you have some "code" 100s or 1,000s of REI (a bunch of them are here in BP Nation) with software engineering degrees haven't figured out.

Search for homes that have unfinished areas, separate entrances, and plumbing and electrical connections already in place.

If you have a pool will it be heated and if so gas or electric?

Also, the tenants will be more comfortable while minimizing their electric bills.

Implementing risk mitigation measures like fire-resistant materials, updated electrical systems, and security systems can help negotiate better rates.

It appears guest somehow (by setting thermostat at below 61 degrees) about $450 of electricity.  

Are you an engineer, an attorney, or another investor with less than twenty years around RE with a bad college education?

Also, if the tenets already pay for their own electric and gas can you use RUBS (if leagal) for water and sewer?