Ask Kevin at Wind Power http://www.windpowerwindsurfing.com/
He is one of the longest term Mistral dealers in business in the US.
If the arrangement is similar to my Mistral Equipe, and I think it is, the daggerboard goes in at an angle as though the leading edge is most of the way forward but not at 90 degrees to the deck, more like 60 or 70 or 50 degrees. When putting my daggerboard in or switching with the larger racing daggerboard I do a lot of fiddling to get it in or out. But not too much forcing. Sorry I can't give a precise answer.