Will a sharpened dowel go through a PME cake card? I have a 3 tiered, 8, 10, 12 inch square tiers fondant covered cake that needs to be transported an hours' drive away. I have silver foil covered foil cake cards that the top 2 tiers are made on. Any tips or suggestions for transportation?

Yes. They're foil-covered corrugated cardboard... a sharpened dowel will go through the cardboard whether it's covered with foil or not.

Will your cake cards be seen? If not, I'd save them for a presentation board and use plain cake boards for the internal structure.