I am planning to make an Indiana Jones themed cake for my nephew in Oct...I am thinking of doing single layer square cakes, 12,10,8,6 and 4. Using WASC...how would I do the supports for this cake being that each tier will only be a single layer? Do I still need to put a board and dowels between each and every tier, or can I stack say the 10 on the 12 in layer, support, then the 6 on the 8in layer, then the topper on its own support??

Support is needed every 4 vertical inches. So the short answer is "yes."