In my opinion you do not need a dba at all, once you get more deals you may consider a LLC, Corp. or some other legal entity. 

One thing which might work in the area are corporate housing rentals.  

For instance, with more rent control restrictions, there are now many property owners who are renting units only as short term corporate, vacation, etc.

I put the property in escrow with my corporation using the language "Vesting TBD for Legal Purposes Only".  

We recently set a HELOC with American Heritage credit union with a fixed rate of 3.99, 3 years draw period with and 10 years Amortization .

I also think if you have the option to obtain a primary with low or no DTV it can offer a sense of security, so long as you secure that home in such a way as to insulate it from lawsuits such as a trust with the rentals in a different corporate entity(s).

I'm a GC and Real estate corporation.

At least in my area they will only lend to corporations (such as LLC). 

Homeowner's association (HOA) and Property owners association (POA) are corporations made by developers for the purpose of enforcing rules for the properties in their community or condominiums.

That is how I have built my business and allowed me to quit my corporate job after two years and do real estate full time.