So you could pay out 120k on a 50k loan if your house stays at 600k in 5 years.Also, if you pay it off in less than 2 years, they make 20% interest on the money loaned.

As for the future I hope to get a Heloc or other type of loan against it in the next few years to pay off the current owner and do more repairs.

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

I bought my first house with two loans, one for 80% and the other for 20%. 

I have a situation where my stairs are not 100% to code in Texas.

However, there can be tax breaks available in different situations.

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.

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.

These are people who fighting cancer, had a death in the family, or otherwise are in a bad situation. 

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