2. This is the most important one: do not cut the dowel even to the cake but to the highest point of the cake layer with an extra 1/8" added. Never let the top cake rest on the bottom cake because this can force out the bottom layer.
3. Cut all dowels for each layer to the same size (aka the tallest dowel).
4. I also have been known to double board my cake boards just to give a little extra support--never can be too careful.
Also, I do love SPS. I would definitely look into it for future cakes.