Josh, I think in CA if you contribute to a house during marriage (in other words, pay the mortgage - or even put a lot of work into renovating it) with funds from money earned during marriage, then yes, it can be considered community property. But you should talk to a licensed lawyer in your state about it.
**Please note, this is not legal advice. I am NOT licensed in California and I am not a family law attorney**
If you are truly contemplating living together for 20+ years and not getting married, then I can see your girlfriend's perspective better. In that case, perhaps buying a house together - WITH A CONTRACT and equal downpayments, sharing risk and reward, etc - would be something to contemplate in the future. But right now you aren't sure what you will do in a few years, and equity in a house may not even be beneficial for her loans, so I would hold pat for now.
You say it's not your responsibility to pay for her education, which tweaks a chord badly in my mind. No, it's not your responsibility, it's her choice and her education, but if you are planning a long-term relationship with someone, you accept that you may pay for them if something happens to their health, job, etc. (And if you have kids, share in raising them.) So it's concerning to me how you phrase it and want to avoid responsibility. Marriage (and even long-term relationships) are about accepting responsibility for each other.
Hopefully you can help her get in a better spot with her finances, where she doesn't get parking tickets anymore, and you'll be less concerned about becoming financial partners down the road.