Whenever you are buying a property out of state you should do a few things to ensure it's as smooth as possible.

I believe the 'fair rental days' data is needed for something completely different (i.e., the ratio of days rented vs. personal use).https://www.irs.gov/publications/p527#en_US_2018_publink1000219036The IRS link above clearly defines when a property is ready and available, which is measured differently than fair rental days. 

If you have them pay it directly, make sure you get them to send statements periodically to ensure the bills are being paid.

There's several things that are trying to create data like you're looking for, but the above way is definitely the most reliable.

@Joe CasizHere’s some sources for market researchZillow and Redfin for historical sales dataDriving the neighborhoods and attending open houses The US census for income and employment data etcMunicipal website for list of employers

Feel free to reach out for specific area market data / trends or a price opinion.

As @Chris K. said, we are there to ensure the property owner's project gets completed the way they've intended.

You will want to ensure that title is recorded properly to avoid title / probate problems in the future. 

Worst case take it out, you don't need it, you pay it back and the money you spent on closing and some interest really could be looked at as a payment towards ensuring security?

I have ideas but best to stick to the data.