2nd(but primary) duplex with under 20pct down in Chicago

Hello all, 

I'm looking to keep my current home and rent it out in the Chicago market. My current payment is around 700 less than I can rent it out for, and it's in an area that is rapidly growing. 

I'm wanting to move into a new unit with 2-4 other units in the property. In terms of monthly payments, the 700 will cover almost the entire difference, and I'm able to put 10-15% down but would have to wait another year to save the final 40k to get me to 25%, which is apparently common in the area. 

Does anyone have any advice for getting a mortgage without the full 20-25 percent down if it's my 2nd mortgage but I'm moving into it as a primary?