Bummer about the outing, big bummer.
I wonder if it just won't work for all people. Shooting with both eyes open really counts on 1 eye being dominant and that one is the one used for shooting. The other just fills in the peripheral vision (and supplies a faint double image that can be dealt with, with some practice). I did some reading and it appears to be indeed the case that some people are neutral (neither eye is dominant, in fact there are varying degrees of eye dominance), I saw the term ambi-ocular used. If this is the case, I would think shooting with both eyes open would be impossible as their would not be a faint second image, but a true double image and depending on which one you go with, the shots may go left or right. I'm not sure, but it would seem to me that shooting both eyes open requires you to be dominant in 1 eye and the greater your eye dominance, then the easier it is to master this technique.
It probably isn't going to be right for everyone. If that's the case, I'd just shoot one eye closed and forget about it myself.
597 VTR, because there's so many cans and so little time!