I do appreciate your replies. I was originally planning to install dedicated chain plates for my runners and will ultimately do that. The toe rail solution will allow me to locate the chain plates precisely. I expect to enjoy a season of conservative Maine coastal sailing as we test our storm sails and their rigging. I don't look forward to the task of their installation but I have the equipment and experience to do it. It is one of those jobs that is very comforting to have done and done well. I would much rather enjoy watching the waves coming over the bow under the drive of a storm jib without giving a thought to loosing a runner or a toe rail! Yikes! I do think the toe rail would suffice in all but the most extreme conditions. Plan for the worst and enjoy the rest!
It would be interesting to hear from others who use their toe rail this way. I am guessing there are more than one yacht rigged like that.