I am a small business person in the Inland Empire ( recycling/transportation/business consulting) , that is looking to learn and invest in the Inland Empire.  

We buy them, rehab, place a renter and then refinance cash out original down payment funds and recycle the same funds into the next project - repeat process.  

I see nothing that indicates that the San Diego market going forward will be different than history indicates (but history does show RE cycles so you need to know you can weather a down cycle). 

Lastly, he is still very new in that space and the complete RE cycle story is yet unknown.

We are applying for an ADU in San Mateo, ca. 640 sf 1 bed 1 ba.Just the permit will cost about 10 k, with all the green building, demo recycling, all kinds of bureaucracies.However, the added value is around $800/sf, or $400k ish.The actual building cost we estimate around 100k-130k.

Should we have a joint bank account separate from our own strictly for the REI business to keep track of funds and cash flow recycling and etc?

I am constantly trying to learn from those who have been through several RE Cycles (the more the better!)

This way you don't have to keep saying up for downpayments and you are basically "recycling" the downpayment money .Best of luck

@joseph M. did mention to me the BRRRR method, Buy, Rent out, Rehab, Refinance, Repeat so that you can get your downpayment back out of the property to recycle on another property.

Once the operating agreement is set, the sponsor can start recycling it for new offerings or simply have their attorney update the few lines that changed for a few hundred bucks.