Spoke to a local real estate agent and some others and so far everyone says that it would be a huge headache (legalities etc) and would cost a ton up front. 

Do not rely on it for legal advice.

If not, any legal considerations for running a SFH as a duplex?

This was my concern as well regarding the legal issue and it being the same person. 

I'm just starting out investing in RE but I want to make sure I'm doing all I need to do properly and legally.

By buying the company, you can avoid certain costs like mortgage reapplication fees, title insurance renewals, and some legal fees.

From a legal perspective, how can you list it on the MLS?

I see on LA County guidelines and CA HCD guidelines that, when converting a detached accessory structure into an ADU, the structure can be expanded by up to 150 sq ft in order to accommodate ingress/egress.Does anyone have experience with using the 150 sq feet rule?

@Henry Clark I'm not interested.NotNot just time to hit returns, I also mean time invested in the day to day on the way to $50k net of expenses, debt service, capex, legal/accounting etc.

We had to hire an attorney and racked up legal fees that amounted to what the solar system was worth in the first place.