Not sure what volume you are doing but setting up a Google Voice account and forcing every interested party to leave a message is a great way to filter out serious vs non-serious callers and prevent yourself from wasting time answering too many calls.I don't have any experience in these type of direct mailers, but have worked extensively on different email campaigns in my previous jobs.

But I assume I can not prevent him to do anything on his own, right?

Do I need to do anything to prevent mold or just let it dry out?

@Christopher Vargas as @Brian Gibbons pointed out it would seem that you are looking at owner financing to circumvent the feature of the hard money lender's program that prevents getting involved in risky projects.

CHAPTER 130-A LEAD PAINT POISONING PREVENTION AND CONTROLThe specific laws about relocating tenants can be found in section 130-A:8-a Relocation of Tenants.For the record, the Law "makes sure that the contractor with the winning bid follows all the rules regarding occupant notification, etc."

Any suggestions for things I  could do to prevent this from potentially becoming an issue (other than paying them to place a tenant)?  

Not sure if you're credit would prevent you from applying or not but it's worth a look.Then of course there's creative finance.  

The older stations do not have the double insulated tanks to help prevent leakage like the new ones do.Most gas stations are not huge money makers.

This may make it harder to buy the exact house you want (depending on the area) but it prevents you from having assets tied up that don't produce cashflow.

Would it prevent me from closing on a purchase if I'm not registered in the State of Florida or the county?