I don’t think this really answeres your question but, for what it’s worth, here is the contraption I came up with.
www.stromtrooper.com
Nelson Rigg SIERRA DRY SADDLEBAGS, Home made racks
So I bought a set of the above bags. I am pretty happy with them so far. I don't think that I will use saddle bags often so I am trying to stay inexpensive. As these are "throw-over" bags, (and staying cheap), I fabricated a stand-off on the left side to accommodate. The bar is 3/16" aluminum...