[VLM]

The tech inside the house visually appears to be mobile home tech not self contained RV tech. So you'll need the $10K septic field, the $10K electric power line, maybe natgas/propane for heating/cooking, a $5K and up water well or $10K to connect to city water if available, it adds up.

(edited to add I forgot to add the cost of a foundation, in the south the freeze line is like 2 inches, but where I live I believe its 4-5 feet, so you're already spending 90% of the cost of a full basement, may as well finish it off and have a basement, but thats another $10K perhaps for something this small?)