If a couple applies for my rental, the 3x income is combined income and I use only M2M leases so if they were to split, you are not tied down. 

@Rahul Bhatt,Have you discussed combining them all into a commercial package with a big enough lender?

As long as everything is functioning and in working order.3.

Think of it as a learning experience.If I was in the same situation, I would look to do the best cash-out refi I could, and take the proceeds and combine with what else you can scrape up and use that for the downpayment on the next place.

Careful in your selection as stains that are silane based (silicon) typically do not breath.I have seen the face of brick and the entire front wall of CMU 'popped' off an elevation due to sealing the exterior of a cavity wall system.My suggestion is to hire an expert such as an architect, building systems engineer or such to give a recommendation on how your wall systems were designed to function.

put together a contract for deed agreement that functions as a rental agreement.  

Or pull some equity and combine with other financing? 

Unsure what others have run into (term wise with their retirement account) but I combined that with my HELOC to purchase a home cash, rehab and rent it out.  

We have since purchased 4 other homes (1 with land, 3 that we moved) and an additional 25 acres that we are using as A combination of long term rentals and air bnb.

The industry has only functionally been around since about 2014; or about 3 years now.