Great Wall of China from Xingang in one day, how?

Hi, Can anyone help? We are 4 adults arriving in the port of Xingang from a cruise ship on 10th march 2013. We would like to take a tour of the Great wall in one day. Could anyone advise if we just got off the ship that there would be tour operators that we could use on the dockside or should we pre-book and pre- pay which doesn't sound too safe to me. Also I use a wheelchair as i cannot walk too far or climb. I do not stay permenantly in the wheelchair, just for walking. Would it be a waste of time me going to the Great Wall or would there be viewing points I could see without the walk/climb?
Thanks alot.
Janet