You should find out what percentage of the rent is being paid by S8 and by the tenant.Tenants have to sign the rent increase and some won't because they don't want their payment portion increasing.It's also highly unlikely a S8 office will approve the huge increase from $797 to $1300.- BTW: the $1300 includes all utilities being paid by the landlord.

Just curious if any particular type of structure has the best ROI or is the most desirable by renters looking to get away from it all and relax in nature? 

Starting with a single-family can be a great way to start especially if you’re looking for a lower-risk starter project where you can get your hands dirty and learn a ton by doing.

Pay it off and then buy a new primary and turn your current home in to a rental.

If it is the going rate in the area, you are most likely okay to proceed as you stated that your rental rate was under market by 20%. 

I was watching a Youtube video by Rob Abasolo that you may like to consider called "How I'd make $10,000/month on Airbnb if I lost everything and had to start over".

Just to confirm my understanding, you are living in a side by side duplex in Miami - you want to renovate the other side that you aren't living with a renovation loan?

I can do an analysis by typing in the address to my module.

I am with Suncoast currently.Remember: cheaper doesn't mean you'll make more money.Start by going to www.narpm.org to search their directory of managers.

Do you or most landlords comply with the city ordinance to get their properties inspected & registered by the city?