Live tree thing is real old hat in some areas. If you don't have a wheeled platform to handle the water proof container you can make one easily enough, just some 2x4 with fair sized caster wheels. Cover with a blanket of store bought paper tree thing made for the purpose. You could go to Wally World and pick up a package of "Moving Men" really slick plastic things designed to put under heavy objects and allow them to slide on a floor. I have used them on a concrete floor when moving safes for secret documents. These weighed several hundred pounds but I could move them single handedly. Be careful, it doesn't reduce inertia, just friction.

Pat