Hakan,
I was a competitor at the LAC so had a close up look of the "M-18HT". I believe the reality was a world class talent sailing the boat resulted in it doing as well as it did.
The "M-18HT" simply did not float on her lines. Mitch felt that the boat could be fast in light air and flat water. As expected, the boat was difficult to sail downwind in breeze. The beams were slapping the waves and Herbie was having a difficult time staying on the wire. From our observation, the boat looked like it was pitching a lot and the waves and chop were not that big (offshore wind).
The boat was no faster than the Bimare boats. In the light air racing, it appeared to be no faster upwind. Downwind, Enrique and Jorge always seemed faster (Mitch lost the challenger berth on a downwind leg).
You do have to remember that nearly 50 kg of weight was added to the boat to make it measure in to the HT class rules. That did not help. Mitch did not know what he was going to do with the boat (I don't think he and Herbie plan to race it). He felt if he sold it, he would remove the 50 kg that was added to it. You could then no longer race it as an 18HT.
Bottom line - you can do it, the rig and platform may be able to handle the loads but you better keep that crew weight very light. I second others in you should consult Goran.
Bob Hodges