I am making a cake with pillars so that I can put fresh flowers between tiers. I don't want to put the cake layers directly on the separator plates because I don't really like the look of them. If I put the tiers on a board like I normally would, can I just set the board on the separator plates? I'm concerned about them sliding off or being unstable. Any thoughts or input? Thanks!

Sure you can do that. You can use double back tape or the ribbly shelf liner hot glued on to make sure things are stable.

Or just stack it up for easy dis-assembly when they go to serve it. I just stack it all up when I do that.