Looks to me like you are combining your skills and passions to make the world a better place, and I applaud you for that!  

This seems to be an emerging strategy in locations with a shortage of affordable housing.  

Huge shortage and they are making a killing.It sounds like you need to keep working and earning income to buy properties?

Actually @Ann North, an architect is more likely to have the skills and experience to know if a lot is buildable.

If you have the skill set to operate strictly as a business you may be OK otherwise don't do it.

Based on your skills and what you did with your current home, I'd use a similar approach where you have a  building with more than one unit and that needs a bit of work. 

Life skills are sometimes best learned doing dirty jobs that suck well.

You might be confident enough in your valuation skills to forgo an appraisal.

My biggest concern is my rehab cost (that is my next skill to sharpen) and my ARV estimate.  

Its actually a part of town I grew up in, and this neighborhood has since deteriorated a bit but because its in proximity to a university campus and other rentals there are no shortage of prospective tenants.