With a .5" channel being routed, I’d say this needs to be 11 or 12 16ths of an inch thick. If we used carbon top and bottom we might even be able to go down to 10, but we’re talking about 12 here if it’s wood only.
This deck with a 26" wheel base will be stiff enough with wood only. Composite after that would make the board overly stiff, and too heavy.
It can be done on a deck with a bottom route that isn’t as deep as this one is.
If anyone sees this, and wants to talk about a deck outside of this deck specifically, then pop on over to the Drang thread, and post there. www.electric-skateboard.builders/t/drang-boards-deck-building-services-design-cnc-etc