Rufus,
Read Swaylocks discussion forum.
This board is experimental finish. Green deck is painted foam. Using Montana Gold paint cans. If you can do a good clear lamination, then painted foam is good way to go. But doing clear over painted foam means you have to be super careful not to damage foam when cutting or grinding lapps. It will take practice. I'm not there yet. Will do some more this way next winter.
Magenta color is one 4 oz lamination with tinted epoxy directly onto white foam. Dark is difficult to get even. The first lam is covered by 7 +4 oz clear lamination. It's not good enough so I won't do it again.
Other way I've done it with success is first 4 oz lamination in clear, then 7+4 with tint. Worked very well. See orange board. This is my preference right now.
If you want full coverage white, I would paint board with 2 component polyurethane paint, the kind used on boats. I've done that, but really you need spray booth.