My primary business is commercial truck repair.

This will help forecast your expected numbers and improve your underwriting skills.I cannot put a price tag on what I learned from this experience.

I am evaluating a few options to improve this situation, one is "status quo" i.e wait another year and then decide since the next rent increase will improve the situation a little, two is to add a detached ADU which I have researched to confirm both feasibility and strong economics, and three is to see about selling the property as a development lot for multifamily, then using the proceeds on another investment. 

Non ad valorem would be taxes that are evenly applied to all properties regardless of value on a per-property basis, commonly for community road improvements, new fire stations, CDD (community development district), or other items like that which impact a small part of the county which those seeing benefit repay over a period of time.

Those exterior type improvements.

Is there a way that I can include a home improvement loan in the rental property calculator? 

@Amer Mallah for instance if you get to a total of 10k for capex, will you keep going or stop there and start over once a huge improvement needs to be made?

I did not raise to market because I was waiting for inherited tenants to leave, make some improvements, then raise rents.

I'm looking for rental properties that would require some minor improvements (cabinets, paint, etc) for BRRRR.

I could have called the Maryland Home Improvement Commission (MHIC) to check his record for any unresolved complaints prior to sending the deposit.