BTW, long term goals are buy and hold single family or duplex homes within driving distance.  

Neither if you are in an area where there are multiple multifamily properties even if they are duplexes or triplexes that will probably be a better option you can find a good median or average cap rate and calculate ARV based on that.

I recently purchased a condo in San Diego, CA (92104) the home values here are continuously raising above average.

and we aren't afraid of a property needing some cosmetic TLC -Duplex, triplex, or quad that we can house-hack; 300k max budgetSingle-family home (3 bedrooms max); would like to stay around 150k if we go this route.

We bought a condo in Tacoma, WA in 2013 that has seen a significant increase in value.

Could I purchase a duplex and add 2 units to make it a 4-plex with an FHA 203(k) loan?

I'm looking into getting a HELOC on my primary residence (Duplex) and while searching around I found this lender called Homeside (http://heloc.gohomeside.com) They advertise 95% LTV.

My advice is to skip the OOS property investing and to instead save up the down necessary for an FHA purchase of a local detached duplex (house hack) that has a value add.  

duplexes?

GEt pre-approved with a lender.....buy a duplex/triplex or 4 plex....Put Section 8 tenants in your rental that YOU screen....That's what I did.....And I live for free.....in the San Francisco Bay Area.Then move out of the property......take the cash out from a refi...Repeat