I think the gravel bar is the best bet. I haven't been caught often, but when I did I tried to get on a gravel bar and sit down and stay low. Lightening is going to the best ground and that's the water. The rocks give you some insulation if you're in the path, at least in theory and that's all you got. Lighting often kills cows and horses that have taken shelter under trees and are 10' from the tree.