Also doing all new plumbing and electric service/panel upgrade to 200amps.

Have you considered domestic violence?

Structurally, the property is in pretty good shape EXCEPT one problem that I cannot properly assess: the plumbing will not hold pressure.

Given the property is located in the Poconos and the property is vacant more regularly as an STR there are proactive measures  you should  be taking such as making sure there are heating sources so that the plumbing does not freeze and ensuring there are no blocks in the plumbing lines with routine checks.

Purchase price: $105,000 Cash invested: $90,000 Property needed some serious rehab, from trees roots destroying the basement walls, to plumbing, electrical, to roofing, landscape.

Does the cost per sqft account for electric and plumbing? 

For instance, plumbing might be updated but not every pipe. 

We did $20,000 of rehab with the new wiring plumbing, rear porch, landscaping, garage teardown & drywall. 

I suggest gradually assembling a reliable maintenance team that includes HVAC, plumbing, and other essential services.Tenants are responsible for providing access to the property.

This is because I'm concerned that even though the things in the house I can see look great things like the electrical, plumbing, or the foundation may need major repair if not immediately relatively soon.