Tireman
I'm up for an education. What is the deal with the straps outside the rub rails. No one has ever given me any good reason why. I have hauled a lot of loads that were always strapped outside, unless there was damage to the rails.
In fact, both of my flats have the rubrails bent in far enough that you mostly can't get the hooks behind them anyway. They were well used when I got them.
Heavy loads done with chain and I almost always go behind the rail, but straps are easier most times over it. Unless you rub on something to cut the strap, it should not be a problem. If you hae a habit of rubbing the side of the trailer on things, I would say there are more problems than where the strap is hooked.
But, that said, I have an open mind and would like to hear a good reason. I am always up to learn a better or safer way to do things.