I'm doing a private tour of China in June. I've been backpacking through Asia since January and will be in Bangkok this coming up week and then continue on through Laos and Vietnam until June. I'm under strict instruction to go get my visa this week. I think I have to show proof of a roundtrip ticket (is this true?) which isn't really a problem except that I plan on taking the Trans-Siberian out of Beijing to Mongolia and Russia. What should I do?

Will a one-way, a bank statement, and personal travel itinerary showing my intentions of taking the train be enough?