My brief understanding of the licensing laws regarding debt collection in a couple states is that not being licensed could prevent you from enforcing the debt, but I'm not an expert here.

Do not let your emotions prevent you from making sound financial decisions.

They’re taking the self-checkouts away there too because they couldn’t prevent rampant theft with them, and many restaurants are going back to paper menus because they’ve gotten such negative feedback from people needing to read the menu and order on their phones (I have dietary restrictions due to a health condition and I hate ordering on my phone because it’s so much easier just to talk to somebody).

It's important to educate yourself on how to prevent it from happening, and then being prepared to act quickly and decisively if it does happen.The problem is pervasive enough in Cleveland that a Google search turned up a lot of news articles, helpful blogs, and other resources.

OR by violating any laws and illegally preventing them from moving in. 

I recommend spending some time educating yourself on how to analyze properties to prevent you from making the same mistake again.

A title report would be necessary to confirm whether or not there is anything preventing a current sale by the owner of record.

Tell the original seller so he can be there with a copy of the deed to prevent the placement of the mobile home?

This is to prevent someone from piercing the veil to ultimately bypass the LLC and sue you personally.

Lots of opportunities to stop and prevent it.