Married to a Chinese national and I want to move to China and open a business.

Now, just hold your 1 year multiple entry visa with 30 days stay duration per entry to go to China, when the 30 days stay duration is up, you can apply for 30 days extension. L visa can be extended twice within Mainland China, then you can stay in China for 90 days continuousely, when you stay in China, you can start to open your business, once you the business registration and settle all details, you can apply for a work visa by showing all the documents for business registration, then change work visa into a residence permit to live with your wife.