Unknowns and margin of safety -> 5k - 8kI just go done removing all the junk from the house for 1850, and the house looks in much better condition than we had initially anticipated.

The #’s were already looking tight and with the unknowns once the walls were opened we backed out. 

After inspections I was able to get an additional $17k off of the purchase price due to previously unknown issues.

You might even find there are things you could improve to increase cashflow either by upgrades, or saving costs.. who knows..Still, there is a ton of unknown variables.

As @Nik Moushon pointed out, someone having a detailed understanding of the zoning code may even be able to point out unknown potentials for the site. 

Its 2.14 acres with a detached 2 car garage, private well/septic in unknown condition.

and unknown by over 95% of the people. 

The big unknown for me is how long will it last.

You have accepted rent from this unknown person and that complicates things. 

Besides the fact that I am not in the same country as the buyers and communication with these unknown people would be difficult, the title company representative who emailed me of the error provided completely erroneous figures for the amount owing, and now we do not know what the taxes actually were that were applicable to my time living in the house (just prior to and for nearly a year after my father´s death).