Catholic Charities, and other sources of rental assistance; local human service providers; food pantries/meals on wheels, etc.; there are also ageing in place agencies that can provide information and resources that may be helpful to some residents.

We could grab some coffee, drinks, food, whatever you want, all on me of course! 

Your property sounds like it would cater very well to outdoor enthusiasts, with amenities/access that probably are not common, so those are things you'd want to highlight in your listing.  

Do they see a projected future for this town or are they catering to the people within the town since they are still cheap prices (after renovating)

Cater to the NYC crowd, and you'll do well. 

My recommendation is to inspect the property and see if their living conditions are attracting the mice (open food containers, trash on the floor, etc.

Or if they move with cause (they cannot feed their family or keep food cold)...you will have to replace the appliances or find a tenant with their own...it's customary to provide a range and fridge in Ohio...washer/dryer are mostly a tenant provided item if there is not an on-site facility...

I'd go to the food shelf and pick up a food donation for them, I'd give them the 50 bucks back and let them know you appreciate them as tenants and your waving the late fee this month as long as the rent was paid in full and it's not usual practice.. 

Just some food for thought.As for verification.

And, make sure the following are also gone:  clothing, toiletries, food, beds--anything that someone might use to live with.