That should hold it securely enough, yet be easy to remove afterward.

You don't specify exactly what the boat was doing in the wind. If it was weathercocking, a skeg should help. However, I would suggest that you do some serious testing with any skeg before you commit to using it. The addition of a skeg that's too large would cause the boat to lee cock, which may make matters worse, rather than better. Perhaps your best bet would be to make a skeg that's more like a long shallow keel than the blade of a typical retractable skeg.