I will be floating a mortar bed on a balcony 4 ft. wide by 11 ft. long. There is nothing to confine the outside edges of the bed. How is this non confinement handled. Do I float to the edge and use a steel trowel to make a sharp cut just short of the edge and just make sure I have it compacted well. Maybe use my hand to confine the mortar at the edge. A little excess will fall off the edge. Is this the way it is done? After reading Michael Byrne's article "Tiling an Outdoor Countertop", it seems I could add temporary edging to the bacony facia that would be at the finish height of the mortar bed. Seems like a solution.