If it were me, I would buy cash flowing, seller finance deals, keeping my debt to income low, low down payments and negotiate competitive terms.

And if they are in low value markets maybe they have zero debt..

It has been bad for the general US populace and good for a select elite group of US and international business interests who now seek to manipulate the masses to believe ending it will be bad for them, the people.Balance is what needs to be restored and the tool as old as the nation to do such is tariffs.  

One factor to consider is your interest rate on the debt.

There might be some hoops to get through with conventional financing with your income situation, but if that doesn't work, you could use a debt service loan.

You can always leverage rentals within their ability to service the debt. 

Also, do you have enough equity that if you sold one you could pay down most of the debt on the other 3?

OR refi one at 70% and get the 45k loan leaving some debt on the line of credit but keeping home 3 free and clear and adding a lot of value to it as well as getting some really good rental income from it.

I look for cashflow to service the debt, repairs, cap ex, taxes, and insurance while the equity grows, my taxes are decreased, and rents are increased to make more cashflow. 

Here's the breakdown of rental income and expense analysis:1.Annual Gross Income: $25,800 (Monthly rent of $2,150 x 12)2.Annual Expenses: $25,800 * 0.40 = $10,3203.Annual NOI: $25,800 - $10,320 = $15,4804.Annual Debt Service: $10,680 (Calculated previously using a mortgage calculator with a loan of $131,775, 7.25% interest, and a 30-year term)5.DSCR: $15,480 / $10,680 = 1.45 (approximately)