Wouter,
I don't think I will ever be able to convince you of the merits of my design through this forum.
I hope to be at Texel again next year, perhaps I will take the boat with me and I will let you see it for yourself.
Unlike yourself I am not a naval engineer only a mechanical engineer.
You sound like you are quite an expert, I would be interested to see some of your designs to see how it should be done.
I will keep you posted as to the final production weight.
All the best
Gareth