Living in China part time

I am a US citizen married to a Chinese citizen and we would like to live in China for 6 months and the US 6 months each year. How do I get a visa that will allow me to stay in China for 6 months? My current one only allows me to stay 60 days. If I can't stay that long how long do I have to be out of China before I can go back for another 60 days?