Some more points about this "test".
Original purpose was to find a "harder" (more scratch resistant) finish that was better than paint over dried epoxy. The second part came from questions about UV damage.
Wet paint and wet epoxy will mix, and may offer a better finish than paint over dry epoxy, varnish only, or just paint.
Mixing paint into the epoxy would require more experimenting to find a workable mix. A little paint made it thick, and it seemed to set fast.
Scratches in paint over wet epoxy did not show as much as in other combinations. I think because it was not as shiny. It weather checked more than epoxy over paint.
None of the test pieces were painted or epoxy coated with any care or attention towards a level finish. The boards with the epoxy top coat have a smooth (slippery) feel. If the wood and the paint are smooth the top coat will also be smooth.
I am not making any boasts or claims about any of this. It is probably worth just about what you paid for it. I was surprised the two mixed and bonded, and pleased they weathered as well as they did.
If the wood is worthy, epoxy and varnish it for a long lasting beautiful finish. If not so nice wood, paint and then top coat it with epoxy and varnish for a smooth,nice looking and long lasting finish.
A high grade of marine paint may work as well or better for about the same cost. I don't know.
Somebody should paint some boards and let us know in a couple of years. That is a long time, but what is time to a board.