Ya, that is an interesting oddity, that the 25 is OK but formal sail rigs are not. I'm a bit out of it lately but I never heard of a list of lakes that the sail rig was ok and wasn't ok, it just comes under the mechanized propulsion piece. Of course if you left the dagger boards home and stretched a tarp between 2 poles, then your OK.
Fall.. and here I was thinking Moose cause you could sail all the way to the Border w/o a portage.
More importantly, how did your son make out? Did he complete the border?