I am doing a semi-naked wedding cake.  It is carrot cake with a traditional cream cheese frosting filling, and a cream cheese SMBC as a very thin outer coating (still seeing the cake under it).  I have done semi-naked cakes in the past, but wasn't happy with the structural support. I had used dowels and cardboard rounds but didn't like how the rounds could be seen in spots if you looked closely.  This particular cake will be 12-10-8 (and possibly a fourth 6" tier).  I could get the SPS system in time (delivery is this Saturday), but I'm not sure how to hide THAT as well.   Any description of how you handle doing tiered naked cakes and hiding the supports would be helpful. It may sound silly but I'm just not sure. TIA

I did a semi naked tiered cake last month (my first wedding cake!:) and didn't have a problem with the cardboard rounds showing. First, you can slightly trim the edges of them so they poke out less and are more flush (or even slightly smaller) than the cake diameter. Also, after stacking, I piped a tiny bit of buttercream all around the cake board area and smoothed with the offset spatula. Worked very well, couldn't see any cake boards. 

That is an easy, peasy fix, @kkforster!  Trim your cardboard round so it is slightly smaller than the cake tier it supports.  Example:  for an 8" tier, trim the cardboard round to 7-1/2"  or you could even use an already cut 7" round.  When you stack your cake, just add a small amount of buttercream to seal the seam between the two tiers.  Perfection!  It made me very happy when I discovered this trick (smile)!

It certainly is no proble if you can get boards just 1" smaller than the cake but if not, just as the others said, trim the board down.