So, I believe this would require me to get additional debt via a separate loan at a rate higher than my mortgage rate.

I have really bad credit, thanks to being a Dave Ramsey follower for a decade but very little debt.

Link-https://www.hometap.com/end-debt-stress-estimate?

Maybe you mean debt to income?  

I know debt can help you scale faster.

Understanding Commercial LoansProperties with 5 or more units typically fall under commercial real estate loans, which have different requirements compared to residential loans.Requirements for a Commercial LoanCreditworthiness: Both your personal and business credit scores will be considered.Down Payment: Typically, 20-30% down payment is required.Debt Service Coverage Ratio (DSCR): Lenders will assess the property's income relative to the debt payments.

If I sold, I could be debt-free and have extra money each month to invest elsewhere.

(I can say that as someone from massachusetts)But people need to be careful as a CFD is consumer debt and if the borrower contests - all that interest they owe you could be wiped out as if you are not sending statements, I believe the law is then interest could be wiped out and considered invalid.

Eliminate debt, establish a budget, and save.

It may not entirely make sense to go from a 30 year mortgage to 15 year mortgage if your debt to income ratio is tight in any sense.