I will not be signing any document with them and have submitted my refund request, as they instructed.

Has anyone ever tried going directly to the manufacturers? 

My area, even the nearby towns are probably not an option, unless the rare fixer upper OR manufactured home (I typically discourage MF) are an option.

It is in the back yard of a 1915 craftsman home, stick built (redwood) home and you can't tell the difference, inside or out.What is flimsier is manufactured homes (those homes are built to HUD standards and appraise differently). 

I was thinking about having the current owner send a letter out the morning of closing with our contact info and new payment instructions.  

California is indeed in dire need of looser building restrictions and it's both a shame and really a humanitarian crisis that their politicians, particularly the local NIMBYs, have manufactured.

There’s a large home manufacturing company that opened its doors in the valley as well.

For one its a great tool, but also it comes with an instructional video series.  

They are classified as an RV and as such are not technically even a Manufactured Home let alone an ADU.

If it is fail/need repair/maintenance as part of regular wear and tear not cause by tenant abuse or negligence.I will also provide a respond to the tenant and offer a new tension style shower rod that they can install themself as a good faith/one time deal (I did shared online instruction/video on tension shower rod install previously).