I'm an American citizen who wish to enter and exit China by Vietnam

I'm American and wish for a one year multiple entry Chinese Visa. I'm married to a Vietnamese and we wish to visit PRC. Can I show my airline ticket from Chicago to HCM City Vn in January for my application? I will be in Vn for 5 weeks on my next visit and I am not sure of the exact dates we would travel to PRC. I plan to visit again in the summer. Can I do this or do I need to make plans on how and when I plan to travel to PRC. My wish was to plan the trip when I am in Vn because we may go by train from Ha Noi. Thank yoiu