I left a message for them both stating that they are still considered tenants and owe rent for Sept. as we did not get a formal 30 day move-out notice (I am taking a wild guess but I don’t expect that their check is in the mail), and that if they call back with their situation and move out ASAP we may be able to work out a deal, pro-rate or something, but either way we need to know the situation.Any suggestions as to how I can legally get them out ASAP, or way to safely clean up the place without having the liability of touching any of their remaining items?

The OP in this situation does know the tree is dead and the liability will be his.

I have been doing the first scenario as I started with one LLC and have added more as I've bought more properties, for liability protection.

If your state allows an LLC to have 1 member it is legal and will provide you with liability protection the same as any other limited liability company if you follow the rules.

I have recently come to understand the importance of cash flow and the benefits of buying assets not liabilities.

I'd like to ask you how you protect yourself from liability in the cabin rental business.

As stated It is not an asset it is a liability.

Based on Marc’s criminal background I wouldn’t want the liability of him managing my tenant relationships. 

It would be my first investment in real estate outside of a residence and I do not have an LLC set up.Should I set up an LLC or would a sole proprietorship with liability insurance be the best course of action?

And I doubt the Fulton County Tax Commissioner would sell such a lien, though you never know.Again, I can't give you legal advice, but this is how I think about quiet title and prior tax liabilities in my Fulton County investments.