Thanx for all the replies. I guess I should look at getting a Tour Pack rack first. (Somehting I was thinking about anyway.) With the rack, it looks like I have more options.
Hmm. I hadn't thought of a license plate bracket mount. In my mind's eye, I was thinking of the flag flying higher up, but it is a cool idea. It looks like they only sell US flags. It would be nice if I could get Canadian ones.