We mirror most of the FMSCR's here. I cannot believe for one second that Motor Carrier Enforcement would fine someone hauling over-width for not putting their straps behind the rub rail.
Standing up, on a 50 ton RGN with only a walking beam on the trailer tandem, with my spring ride tractor. I made sure I positioned it to sit on as many cross members as possible and used every 1/2" chain I had. I only had to take it about a hundred miles, but that was a scary ride.
I've been doing it for years. There is always someone that will find fault in anything, including police. If you know what you're doing and take your time, then you have nothing to worry about.
All tiedowns and other components of a cargo securement system used to secure loads on a trailer equipped with rub rails must be located inboard of the rub rails whenever practicable. Also, edge protection must be used whenever a tiedown would be subject to abrasion or cutting at the point where it touches an article of cargo. The edge protection must resist abrasion, cutting and crushing. If in doubt look in the "green book" asking drivers will get a ton of different answers.
Here's one for the group what's the WWL for a chain that runs from one side of the trailer back to the same side? Like a u chain hook up on a shotgun coil