This sounds like how to not eat and drink for the rest of our life. Getting married and using a bank is just an option but paying taxes, investing and getting a job is a part of survival. Taxes are like funds for the security of peace and good governance. Investing and getting a job are quite the same. Investing time, effort, and money is required to get a job and to do the job.
Getting married and using bank services are not strictly optional. I would rather say they are close to necessity. Live-in relationships are not stable. So if you want stability in your family life, then you have to go for marriage. But the risk will always be there. In case of a divorce, be ready to part with a large portion of your wealth. Regarding taxes, there is no escape unless you can find some loophole which is 100% legal.