I think the tables and the balls should be allowed to become dirty (played in) so to speak. Over the course of a tournament the conditions will get tougher as will the competition.
I just had a refrigerator delivered yesterday, these guys used "shoulder dollies" I was impressed. With the weight on your shoulders your hands are free for balance. To me, the worst part about carrying slate is how hard it is to hang on to when vertical. These dollies may be worth looking into.