I'm considering doing a private money raise in order to secure more rehab funds to continue the renovation on a 3plex flip in Houston, TX and then push the ARV to a much higher value from $275k to $500k+.

Verify yourself if you are required to register your property as a rental, consult an Attorney who has actually appeared in at least 100 cases where your property is located.

This is a generally safe way to invest since the loan is secured by real property. 

Your location, property configuration and area demographics will tell you a lot about what you should be targeting.

For cities, will your jobs have a physical location?

Yeah go to the closest gas station and sit there for 10 min, who is going in and out are more people walking in than cars, the location of an investment is the one thing that you can't change.

All my units are in A/B class neighborhoods with 95% of my tenants in healthcare - nurses/Doctors and all my units are wirelessly controlled with security system, wireless door locks...

At the end of the day you are not going to get enough income to justify all the headache and extra funds you must layout. 10kish, furniture 24-hour security system, yard maintenance etc.  

These are slow growth approaches, but they make it much easier for some folks to get their start, and after one or two transactions (2-5 years) a very secure foundation is laid and momentum can increase. 

Short term rental given the location?