The home is above average for the area, but rental demand has been tough.

The "substantially all" material participation test is another option but it's more ambiguous and difficult to prove. 

Is it this one: https://www.loopnet.com/Listing/3630-Trowbridge-Ave-Clevelan...If it is, very challenging to put something here considering it's a residential neighborhood and there's probably a lot of work to do to get it up to snuff... cocktail bar might be a tough sell given demographics but otherwise could be an interesting project!

Behind the house parking is a huge plus, but can be tough to find.

Can they prove how long it takes to rent a vacant property?

Even tough, I am in information overload right now and working a full-time job at night.

@Paul Bogard going to assume you are buying this proeprty to live in while you "house hack".First, you should understand +95% of real estate agents ONLY know how to sell owner-occupied properties and are almost useless for investors:(Find an agent that has rental properties themself or can PROVE they've got successful repeat investor clients.Secondly, you can greatly improve your cashflow by renting out your other bedrooms.

Your property management experience will help, but getting property management on a one-off Section 8 out-of-state will be tough? 

I have spoken to my neighbours but they do not know who the HOA board members are ( it is a large complex with 100 + townhouses).It is very strange but it has not proved to be a problem in the past as the management company deal with the properties externally ( eg painting ) and the common parts and have always done so competently and individual oners deal with the inside of the properties.They are now proceeding with the painting without doing anything about the termites.

South Carolina's 6% Non-Occupancy TaxYes, the 6% property tax rate for non-owner-occupied properties in SC is real, and it can feel like a tough pill to swallow.