;^) Me too it seems!I seem to have an unlimited amount of time to contemplate this issue ... see my post in AAS.
Scott,
Big Easy has a Double Spreader Rig. TOTALLY different beast in terms of setup. Also in that rig if your rigging is continuous or discontinuous factors as well. On double (or more) spreader rigs, the sequence is much more complex; on our 36.7 it takes half a day. And you do leave them loose as you dial them in. Then you tighten.
As for the EXACT point, its not super important. Within a inch and you'll be fine. Pulling the shroud down to that point as I described DOES however give the exact spot mathematically for the spreader tip (I'll leave the proof to you but it's easy). Keeping them tight is the important part.
I'll concede that some very small boats the designer probably figured that the loads were not enough to worry about. But it doesn't invalidate that they would be better clamped.