@Stephen KunenProviding substantial services to your hosts provide suggestions that you should report it as schedule C as opposed to schedule E.Substantial services include but not limited toConcierge, meals, housekeeping, cleaning, entertainment etc.A pro of reporting it on schedule C is that losses are deductible and not subject to passive activity rulesA con is that income will also be subject to self-employment taxes in addition to income taxes.

Since this thread was revived, here's an update:-  The Book on Flipping Houses is on Audible-  The Book on Negotiating Real Estate is on Audible-  Recession Proof Real Estate Investing is on Audible-  The Book on Estimating Rehab Costs is NOT on Audible, as it contains a lot of charts, which wouldn't translate well to audio format

If things went south with the SO, would I have any extra rights to the ownership of the house if I am able to show proof that I have been the "breadwinner" and paying for the house mostly on my own?

Go to the top of the page, click on the magnifying glass, and type Section 8 in the search box.

I’ve seen that work once trust is established and you’ve shown proof of concept.

Then, despite my having a quote, our acceptance, pictures he posted of the job in progress, an invoice upon completion of work and proof of payment, he denied we ever did business with us!

I am renovating the bottom unit of my duplex and am considering sound proofing options.  

However, without that, you really don't have any solid proof demonstrating it wasn't like that. 

If you've lived there 2 out of the past 5 years or have some proof of that, why  not sell and get a tax free gain.

While you might be able to use future rents as proof of income, that is going to require some extensive documentation from the previous owner.Best of luck to you.