The contractor took 3x as long, raised the budget by 70% as kept finding new little things it needed.

If you have excellent (760+) credit, can hit a 1.20+ ratio, loan amount is where it needs to be, it's a single family long term rental and you're okay with (and state/lender allows) a 5-year prepay, low 7s is possible.

That is a long time without rent.  

I assume this is deal one but as long as they have good credit they can get entry level bridge loan terms. 

Hang in there for the long haul.

I’ve already texted the seller for more information, including how long the daycare has been there and how much the woman is paying in rent.

I’d look at how long you plan to live there first as the longer you live there typically the higher you can raise rents organically due to inflation and the overall cost of living increasing every year.

Mortgages and other long term debt has not been impacted. 

If I was going to create one PA would be the very last state I would do it in. 

You are not crazy :) cap rates on storage got pretty crazy in the last decade as the space has become crowded and money was cheap, starting to see some reversal of that now, but its tough to find deals at a true 10 cap (10 x NOI or NOI / .10).