Pleasant surprise: it's possible and not even difficult to get a very nice coat rolling and tipping paint. I only put one coat on and the result was beyond my expectations. I use two part paint, thinned with a special thinner for brushing. The paint self-levels really well. Biggest problem was small rubbish getting trapped in the paint, although I cleaned my attic/workshop thoroughly. Next time I'll wet the floor to get rid of some more dust in the air.
Work on the main hull is starting once again. My brother helped me to trial-fit the centerboard.
Problem: the centerboard can't fold all the way because one edge touches the hull too fast in the area where the upper part of the board folds in (look at the picture below, you'll understand). Problem was solved by put a 45 degree bevel on that side. It seems like with more parts on this boat the design doesn't allow for a big margin for error.