I know that you need to support anything 4" or higher. Couple questions:
1- the cake board; should be it a 6" board for a 6" cake or do you use a smaller board, like a 4" so that you can't see the board?
2- how many dowels per tier? One every 2 inches?
Any suggestions you have for making stacking easier?
Use a 6" board for a 6" cake. Cake usually shrinks a little during and after baking, so you can crumbcoat/ganache to the edge of the board, making the cake 6" again. Once you buttercream/fondant the cake, the board will not be seen.
I only use SPS, not dowels, so can't help there, sorry.
what is the sps system? i have seen some systems out there that are very expensive.. i don't think that I have seen this one. Please explain the sps and where do you get it? I might do a regular post to find out.. not sure if this is the correct one