Heat often isn't distributed throughout a building equally. 

I know a lot of people have been successful using a lot of debt to build their portfolio it's just not the way I do things.

There is not a bathroom in the building so unfortunately only option is a Porter Potty.

I am open to other scenarios.We have access to $200k ish in equity in our primary.We will soon have access to another $100-150k for retirement/investing/IBC/etc.I would like to move into my young family into a (new build or fully renovated side by side) duplex.

You can get the ready to assemble ones.

Option 2: Purchase additional properties and build portfolio I know that there are some tax implications to no having the mortgage payment to consider.

If your focus is to accommodate your mom and you can hold onto the property for a bit, I think you could definitely build equity and eventually generate cash flow from it.

Once that rehab is complete, and a few minor updates to the cottage house in back, the 3 units will be ready for many years of rental income.

I have been investing in Toledo, OH since 2009 and owned 2-12 unit buildings and find they are way too hyped (read lots of guys from BP want to pay too much for them) and the reality is residents in Toledo are ultimately seeking a house with a yard and a garage so as soon as a resident improves their financial situation they move into a house.

I am also nervous about it not cash flowing at all but I think buying in southern California and holding long term is an almost certain strategy to build wealth.