Would you turn a Duplex into a Fourplex?!

[Andy Keffer]

Looking for a house hack project and found a "duplex" that used to be a fourplex. There are 2 - 2bd 2ba units upstairs mirroring one another. Downstairs these 2/2 each have their own 2 car garage. But in the back there used to be 2 1bd 1ba apartments that haven't been lived in for a long time and need gutted and put back together. The reason it is not a fourplex to my knowledge is the septic system it is on is only big enough to support the 2-2/2 upstairs. So, the questions is... If the only thing stopping you from this was all the risk of the unknown what would you do next? My list - get a septic upgrade quote, get a renovation quote, negotiate with seller, find the money... what am I missing?