Most of the duplex to quad you see that meet this rent to cost ratio have one or more items that disqualify it from it being something I would purchase.However, seeing the land is already owned and it is to be better leveraged it seems to be fairly easy to achieve far better than a 0.75% rent to cost ratio on rented ADU buildings. 

There are, however, costs for licensing, continuing education, access fees, etc., so just weigh the pros and cons and see if it's right for you. 

With that in mind, probably the ROI is not going to be great, because you have all this money in equity, no leverage.

If they don't and you foreclose you have some pretty strong leverage.

The City of Austin recently passed a resolution to "educate homeowners who could get taken advantage of by low offers, with the promise of quick turnarounds."

Very nice people, very supportive, always with an educational component. https://www.meetup.com/Masterminds-of-Cen-Tex-Real...Start by reaching out to a couple of local RE agents and let them know what you want, set up alerts for your criteria on Trulia, both for homes for rent and for sale.

Given the same deal ...Should I try to leverage the most amount possible and buy as many units as possible ?  

My relentless drive to self educate has been going strong ever since.

This is where I saw an opportunity.I saw the potential for my grandparents to leverage the equity in their two unit home to pay off their new purchase in full and have the rental income cover the debt service.

Right now I am working full-time and would love to partner up with some other wholesalers to leverage our time and skills.