It's pretty routine for people to leave camping gear and backpacks at Trail Camp. You need only a small day pack to carry water and snacks to the summit. The main risk is marmots and other critters chewing through to get to food. A bear canister should help here. I have not heard of a case of theft, but I would not tempt fate by leaving expensive electronics like GPS or camera in the tent. Ordinary camping stuff will be O.K.
