So I know this will come at risk of being an outcast, but I too will be attending and not wearing gold. I went to two stores today to find something in gold that either I liked that I would wear other than at the game, or that was cheap enough to justify spending the money for one game. Couldn't find either at Kohl's or Sam's Club, and that's all the time I could spare. And my 4-year-old son also doesn't have any gold shirts, so that's just the way it is.
I would have participated, but it was too much of a hassle for me to find something that worked. Granted, I could have started looking a month ago, but I didn't.
As far as the game goes, don't give people grief about not wearing gold. Don't call them out or tell them they aren't good fans. We have a hard enough time selling tickets and getting new people involved to think that if they are hassled at a game about their attire they will want to come back again.
In reality, the only way to get this to truly work is to lay out T-shirts on every seat as a giveaway. There has to be a sponsor that would do it. The Twins have giveaways all season long of much higher quality than the 75 cents per piece it would cost to mass produce a bunch of T-shirts. Once per year if they are going to do this Gold Out, it is the only way to go.