Advice: Reach out to your lender or someone experienced with streamline refinances who can help advise a more accurate estimate for you. 

So as a % of total asset costs roofs, turnovers, etc... are a much higher % cost than on a more expensive higher rent roll property. 

About 5 years ago we hopped in a RE syndication and pulled out of it recently to take a more active role in our investing (returns where meh), along with trying to supercharge our financial goals in retiring early. 

If those home is paid off and the equity is only needed for a short time, taking out a more traditional HELOC might make more sense.

I think I will replace the counter sink with a vanity with sink, get rid of the medicine cabinet/mirror, with a more modern mirror, get rid of the shower pan, and replace it with something else (suggestions?)

They have undiscovered areas to the south or you can look at Ambergris Caye to the north for a more developed area, although I’ve heard they are having issues with water.

While margin borrowing is doable - I think it opens you up to potential pitfalls that could be avoided going a more traditional route.  

Take a more long-term view, what happens when you continue to reinvest your cash flow and make your assets better?

Does anyone have a suggestion for a more seller friendly tool?

This approach involves actively investing money to generate returns instead of letting it sit idle, potentially offering a more dynamic and rewarding financial strategy.Cardone also emphasizes, "Cash flow is king.