I've crunched the numbers on a typical 300-400K mortgage and the "break even" on refinance costs and rising rents is about 12-years. 

A "pre-approval" sounds like a "consumer" mortgage rather than a commercial loan for investment real estate, is that correct?

IMO, there are better and cheaper ways to do it.

Then of course, you are also hoping for appreciation.While it is attractive to not have to worry about cap-ex for a few years, many maintenance issues are usualy tenant-caused, so there may still be ongoing issues & expenses needing attention.Another option may be to buy an existing cheaper property, that's still in overall good shape.

For residential mortgage, an LLC needs two years of its own tax returns or occasionally, a local credit union where you have an account will ok it.The bigger question is about your partnership.

Here are 10 tax tips every homeowner should know:1️⃣ Mortgage Interest Deduction: Deduct interest on loans up to $750K!

That way I did right by my realtor-friend and also did not pay interest at mortgage rate. 

@Brandon StainesOption 1: do nothing you stay on mortgage and good is you still own 50% of house but bad is if she defaults then it hurts your credit tooOption 2: have her buy you out but that would require a new mortgage at a much higher rateNot much else you can do.

There are DSCR programs that go down to a 620 mortgage FICO score-higher credit scores will have better rates.

My online license course barely mentioned regular mortgage financing.