Everything went off mostly according to plan. She was, however, able to open the box - so I put my hands on it and went to a knee as smoothly as I could manage. My voice became a bit softer than I would have hoped when I asked for her hand, but she said "yes"people clapped, and all was well with the world.
On the way home from the restaurant, she told me (with some prodding on my part) that I was the 5th person to ask her - but the first and only proposal she had or ever would accept.
I R Happy Guy!
Thanks for all your help, suggestions and support!