I recently purchased a four-unit near USC/Exposition Park which is an area that is still relatively affordable but has been changing a lot. 

Check out the CRREIA group which meets in Clifton Park for meetups.

What about drive approaches, parking lots, site lights, landscape, irrigation, etc.? 

In addition to those above-referenced issues related to conversions, the additional unit(s) would require a parking space and enough lot area/gross floor area to meet the requirements in 9-703. 

Find a park a distressed park, find some distressed trailers, put your husband to work. 

As long as the location was in the path of progress, and the units themselves had already or the ability to add features like off street parking, in unit laundry, etc. 

Parking will likely be your biggest hurdle.

Property is in downtown San Jose location with possibility of new parks next to our location being built and also new constructions around our neighborhood.2.

Quote from @Jon Parks: I think it's safe to assume your capital is gone in failed business ventures.

I toured some apartments in August and there were multiple uhuals parked out front.