But in the area it’s possible the water freezes in the winter.

You are in treacherous waters here ... the prospective tenant told you they were receiving disability making them a protected class so be careful. 

Even a $50,000 home needs a new boiler, roof, water hear, and to repair regular wear and tear.

The owner has been selling the park owned homes either for cash or on a rent to own.Taxes are $45k/yearThis park is on city water but a private sewer.

You cold be getting all kinds of title issues with a tax sale property if you don't close it through a title. escrow company. 

The tree keeps growing and producing more fruit(money) over time and you still have the tree which is likely worth more than when you acquired it.You have to make sure it is watered and fertilized and maybe pruned occasionally.

I've put almost $25,000 into the house with a major repair for the well water system. 

We are also going to have a US company cold call the owners of off market properties as we find that yields better results than just mailers.

(Home Depot has about 40 different kinds) You want one with a lot of silicone in it for water exposure.fwiw, what you fill the crack with doesn't really matter all that much as it's just a way to keep from needing so much caulk.

I know that if you cold call people, you have to scrub your skip traced list with the DNC (do not call list).