Me and my brother started cutting out the beam mount openings. It's a bit scary to cut such big openings in the hull, but it needs to be done.
It took us a long time to get the hull level. We worked on one support at a time, using two car jacks to fine tune the height. The topside of the straight, long, piece of MDF you can see sticking outside the hull was our reference while leveling. This piece runs through the hull to both sides, and is clamped on the inside at the right height - that is: at the gunwaleline which is (and should be!) marked on all the beam bulkheads. Maybe it's possible to use a laser level to mark all the lines at the right height on the sloping areas, but we did this low tech with a tube of water and a yardstick hanging or standing at the right distance from the top of the crossboard (see above picture). Hold one end of the tube near the yardstick and the other near the hull, make sure the water is level with the end of the yardstick, and make some marks on the hull. Connect the dots and you have a - granted: not very accurate, but accurate enough - level line to work with. Trial fit of mount. We thought that I had made a very, very,very, very big mistake somewhere earlier on when we first looked at the result. The outer end of the bracket area on the front of the front beam mount was not inside, but a few cm outside the hull. The stick I'm holding indicates where the 'wall' of the beam mount will be formed. I was very concerned as I couldn't find a clear reference to this gap in the plans.
That was too much for our nerves, and we decided to call it a day. Back home I was relieved to see that the F22 build for Oliver doms has the same protruding area on the front beam mount assembly. To be absolutely sure this is how it is meant to be I mailed Ian. I don't want to take any chance fitting these important parts. Now just hope and pray it's ok.