As far as I'm concerned, it's unsafe to raise the mast on the trailer. Suzy Granger was hurt VERY badly in a fall whilst raising the mast on the trailer. It wouldn't be so bad if the boat is left folded in the water, I suppose. But then I have no cabin-top hardware for the babystay/temporary shrouds, although I could rig something up.

My Precourt shrouds are set up for the raised-mast position. They don't tighten that quickly, you're going to find it a real PITA to adjust every time you rig. That is to say, I would be quite sure that any time you've saved by not having to raise your mast is gonna be eaten up with messing with the shroud adjustment.

We drop the boat in the water, unfold at the dock, motor out a bit into the embayment, anchor, and finish rigging.

The shroud diametre?
http://www.precourt.ca/shopcart/default.php?cPath=25_33&language=en

Ask Erik Precourt for specs - your boat is larger than mine and I wouldn't venture to suggest anything. Besides I have found les Precourt to be helpful, supportive and very nice folks who produce excellent products.