Great write up, choose your poison, but different products are suited to different situations!

This part is important, and you must ask this pointed question (in writing, preferably) to someone at the financial institution with sufficient understanding of the banking industry. 

Did you mean to write that this guest booking covers  2/3 of your annual expenses?  

After writing a book on multifamily and then banging my head against the wall for years trying to find apartments that made sense, in frustration, my firm transitioned to start investing in SS and MH parks.

I personally have a number of HELOCs on my properties, and as a lender with access to dozen of investor's HELOCs I can say none of them restrict the use of the HELOC, or even require a cash out letter of explanation.Credit Unions write their own rules!

I have a deal I have been negotiating but they asked for what I'm thinking in writing. 

People like Susan will immediately write off  a responsible tenant because of some bum. 

That may have been from a transaction you had along the way by writing a check or putting your account number for automatic bill paying.

Getting the official legal advice in writing from an attorney rather than a CPA, since they are officers of the law, can give you greater protection than just advice from a CPA. 

IF so, have him put his suggestion in writing so that you are covered in the event of any mishaps of liability.