Do I need to cover my cardboard rounds (under the cake itself) with wax paper if I am using the SPS system?

Thanks in advance for any help-I'm obviously trying to skip a step here since I am covered up in cakes this month!

I wouldn't... the waxed paper could get sliced up and served with the cake. I'd only use waxed paper on the top surface of BC when another cake board or plate is stacked to help prevent it from sticking.

I don't there - but I do (as CWR41 suggested) on top of the ganache or buttercream when stacking straight.