Staying in Shanghai - Hangzhou West Lake and Xitang possible in a day trip/round journey?

So, I'm staying in Shanghai for three days, and my girlfriend wants to take a day trip to see the West Lake in Hangzhou. My choice is to see Xitang.

Seeing as Xitang is between Shanghai and Hangzhou, and accessible from both places, I'm wondering if we can do 1/2 in both? My plan would be to go to Hangzhou early in the morning from Shanghai (maybe arrive around 9am/10am), bike around the West Lake and maybe see the Lingyin Temple. Ideally spending around 4 hours here or so then leaving for Xitang around 2/3pm. Then spending four or five hours there before getting back to Shanghai late in the evening.

Is this doable/feasible? If so, what is the best/most efficient way to create a round trip, starting and ending in Shanghai? Accommodation in Shanghai is already booked, otherwise I would have looked into an overnight stay somewhere.