Fastest option would be to sell it to an investor, and they either pay cash for it OR if it would qualify for a DSCR loan (for rentals) it can close in 25-30 days. 

While you noted you are paying from business accounts, whose name is on the loans?

You can also run your STR in your personal name or elect to start a company that operates the STR i.e. branding.If you do not qualify or for some other reason do not want or cannot qualify for conventional financing, you will likely have to go to some sort of DSCR or other business purpose loan route, and they will actually require you to put it into an LLC.

No Loans.

I also thought about just taking out an FHA loan (since my wife and I both have 750 credit scores) and buying a house and renting out my mobile home to cover the mortgage.

Option 1: I was thinking she gets her $650k, she holds the note on a 40 or 50 yr amort loan.

I am struggling to find any lenders that will do a line not a term loan.  

they send out governance votes on certain things like sell the property or take a loan against it.

Sold to a Veteran who used a VA Loan Lessons learned?

They can push a DSCR loan into negative cash flow territory which makes the rates even worse.