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".

View report*This link comes directly from our calculators, based on information input by the member who posted.I’m considering purchasing two investment condos to help pay for my children’s college tuition in 13 to 15 years.

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?

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

Although that would be looked down upon by a lender as well because of the inherent risk of lending to someone who has too much on their plate. 

Our options are to put the money the stock market, buy a multi-unit property, by an established business, payoff the 3 rentals for cash flow, or get into hard money lending.

I've not yet invested in my first property, but I plan to purchase my first one by the end of 2023.

Quote from @Danielle DeCormis: Working on a deal where the home has been foreclosed on by the bank but they indicate they have no knowledge of the solar panels or whether there is a lien. 

Is this near Franklinton by any chance?