He told me he owned a few mobile home parks in town (they were large and had high lot fees) and this is what sparked my curiosity.

Meaning the keys were generic to each unit and could be stolen without sign of breaking in. This

Good you are researching this topic - I also love subject tos and have written a book on the topic.  2. 

If the numbers work in California, and they may not, then go for it. 

I was sent an offering memo by a broker selling a multi-family building in an area no reasonable person would even consider affordable housing material yet the marketing materials made a point of emphasis to detail how the property would satisfy the need for affordable housing.

@Ken Kast  Focus on the viability of STR's in Northern Grays Ferry not STR's in Philadelphia more generally.

Over the past 10 years, he and his late wife poured their hearts into building this home (with permits, of course).

I found Rehab Financial as one of the best hard money lenders in Philly, but I was wondering if any of you have worked with them in the past.

My budget is in the $200-250K range.Please feel free to let me know if additional details would help, and thank you in advance for your time and advice! 

I have been struggling finding fair priced reliable contractors in my area.