> What if you were to epoxy saturate all the panels before beginning any
> work? This would eliminate that problem and would further protect them
> from being marred during construction. What do people think of this idea?

I've built my last three stitch & glue kayaks that way. Roll on two coats of epoxy right after cutting out the pieces. I use a foam roller and foam brush to tip out. It takes care of any discoloration problem and saves many coats of varnish for the finish. (I think anyone who uses paint on a wooden kayak...I won't say more.)