Or maybe a subject to if they have a decent-sized first mortgage?

What if there are no other units of similar size similarly situated have recently sold? 

If you indeed want to just be involved in the deal and thus want your piece of the pie too, then it would be approached as a regular transaction where you're only owning 25% of the property and thus the lender would collateralize your portion of the asset. 

- Can I take the full 30% solar tax credit if I house hack a portion of the house?

- Can I take the full 30% solar tax credit if I house hack a portion of the house?

I had to jump in though because I was advised that you can be sued for the equity in your houses, not for the remainder with a loan on it (basically that portion is considered your lender's, so can't be taken in court).

Only a portion of the rent is covered.

First start with defining your investment niche (asset class, location, size, strategy).

If I'm able to speak with the guest, I may make an exception; for instance I may allow them to bring a larger dog than the 50 pound size limit that is listed. 

If it's an opportunity - regardless of the size of the property - it's an opportunity.Start kicking the tires...the market will tell you if you can do what you're thinking about doing.Best...