Its great for me where I need to adjust to paying a mortgage and was worried about my monthly payment a little bit! 

You’re not going to find a safe way to do what you want unless you or the “buyer” has enough cash to pay off the note. 

So I put $1600 on a credit card for a down payment and then pay $500 a month until the full amount was paid off.

This creates two loan payments ($100,000 of equity and $300,000 on the new mortgage).Key NumbersHome Equity Loan Interest Rate: 6%Mortgage Interest Rate: 7%Rental Income: $3,000 per monthExpenses (management, taxes, insurance, maintenance): $800 per monthIncome and ExpensesMonthly Rental Income: $3,000Monthly Expenses: $800Monthly Mortgage Payment: $2,000ExplanationThe investor earns $3,000 in rent each month.They pay $2,000 on the investment property mortgage and $800 on other expenses.This leaves $200 profit each month or $2,400 per year.However, you have to pay $6,000 interest on the equity borrowed.This leaves you with an annual loss of $3,600.While the rental property generates positive monthly income, the interest cost of borrowing the initial $100,000 results in an overall loss.

My goal is to offer an affordable monthly payment that competes with renting a comparable property and offers a benefit to paying a bit more to "own". 

No need to pay big bucks for this. 

VA loans are the only loans that allow this, and there is no rate penalty for it no longer being your primary home.With that in mind, you could do a cash out refinance today at a higher rate than current market rates which will create profit on the loan, we can take that profit to pay for your closing costs.

Every where you turn there are STRs going up on the market fully furnished because they couldn't pay the mortgage and bills with the rental income. 

I used $80k to pay off personal debts and $50k to remodel it by myself with my two hands.

For anyone that has been a buyer or seller of a seller finance property, what method of payment and tracking did you use for buyer to pay seller monthly?