I have a CHB and there is another one in our covered marina, along with other Trawlers. All of them have their masts down while berthed. I am going to be a bit surprised if anyone makes covered slips tall enough for Trawler masts. Regardless, don't forget that water levels change due to tide, if you are on the ocean, and in our inland lake system (Lake Union and Lake Washington in Seattle), due to operation of the locks to the Sound and who knows what else. The difference over the season is a couple of feet for us.
I would have a plan B for lowering the mast when berthed if I were you. The problem with doing that with the CHB is that it cuts your aft deck in half when you lower it, so you can't party there without doing a limbo dance under the mast (and boom and rigging, if you have that). I rigged a block and tackle to the rafters over my slip so I can raise it part way at about a 60° angle off the mid deck when berthed, but I still have to drop it again before departing, then raise it and attach shrouds after leaving the slip, then the reverse when returning to the berth. It's a PITA.
Another guy in our marina with a GB36 cut his mast off in the middle and had a custom articulating hinge put in to the mast at the cut. He drops the top half of his mast onto a wooden cradle he made with legs that extend to the aft deck. It looks funny, but it solves the problem of having the lowered mast across the middle of the aft deck. Of course, the cradle legs detract from the view a bit, but not like having the mast at waist level.
