You don't have to squeeze every dollar out of the rental, but by your own admission, you're 20%-28% below market rent.

How is that any less fair than colleges that charge application fees then choose only the most qualified students for admission?  

If you can find that, I think coupled with your video evidence (although it probably wouldn't be admissible in court) could help you get them out quickly.

Then, if he ever causes any issues, remind him that you have a written admission of tax evasion that you're prepared to forward to the IRS...  :-)

You introduced to him a completely new way to buy a home by his own admission, he was probably just asking out of curiosity more than anything. 

You are performing the services of a property manager and you by your own admission are not licensed. 

Comment:   Personally, and I could be wrong, but I think the Listing Agent did get the Seller to sign a release of Earnest Money (which might include an admission that Seller agrees that the Contract is cancelled) and now the Seller has remorse and regrets their decision.Good luck.

Any judge would see not including the manufacturer as an admission that their assertion was disingenuous on its face.

How long it takes and how essay is to do it if you do not leave in the area? 

I try to avoid writing lengthy essays.