Thanks Swiebertje, I wonder why you think 2 pot paint is the best, I was thinking about using garage floor (one pot) paint.
I have heard of people scattering sugar on wet paint then dissolving it to leave little craters where the sugar was, painting it again to smooth off any sharp edges. I don’t want to be fighting off wasps though so maybe sand is better. My boards are both in two pieces so I shall be looking to reinforce them with battens on the underside as you describe.
I don’t suppose it is feasible for you in the Netherlands but it is Beaulieu Boat Jumble this Sunday, thoroughly recommended for anyone looking for odd fittings and cans of paint and varnish at knock down prices.