As a result, we had to apply for a new gas line separately.

Pay yourself "rent" into a separate account to use for the property/future investments and get a feel for what the actual cash flow would look like.

Does anyone have a recommendation for either national or local lenders (I’m based in LA) that will include short term rental income in a debt to income calculation to help finance a separate conventional mortgage?

You can separate and protect each of your rental properties.

In Joshua Tree, your cannot STR two separate structures on the same parcel.

My W2 job means that I don't actually spend any of the profits from rentals, but they are all self sustaining and separate from my W-2 job and living expenses/mortgage on personal property. 

Poured a new driveway and separated the Main unit form the second unit on the property to create two private living spaces.

SEPARATE LAUNDRY CLOSETS!

UPDATED KITCHEN, FLOORS, SEPARATE LAUNDRY CLOSETS!

Multi units prefer 2+ bedroom units, 1,000+ square feet each unit, side by side is ideal if possible, want at least electric and gas separate, any area can work for these as long as it isn't a D area, but usually B-C class works best since buying these primarily for cash flow.