Not sure what the layout looks like or location - but in a solid location, which I'm assuming since it's an STR, you should be able to in the ball north of $800-1000 per room and even more so for the rooms with private baths.

I currently haver a private mortgage on the property that I will need to refinance in about a year or I have to pay a baloon payment. 

This can be hard money lender, private lender or bank.  

My STR is in a city where it is legal in private but not in public.

I financed this deal using a combination of cash and a private lender.

Private money lending.

It's not in the spirit of the rules and exposes you to problems downstream.

@Sandeep K MamidiTo flip properties effectively, use market knowledge, research local trends, and innovative financing options like private money loans, partnerships, and syndicatation.

Quote from @George Goldstein: You know how when you buy a used car from a private seller you tell the seller to say he sold it for $3000 instead of $18000 so your dmv tax is lower?

With private patio and great Williamson County SchoolsWhat made you interested in investing in this type of deal?