Well the way I understand how the Andersen hitch is made is that instead of carrying the weight on the whole flat bottom of the pin box, your now carrying it at only the locations of the set screws against the pin box so in an application like that I guess it could bend the bottom of the pin box. Yes the pin is doing the pulling but the flat is holding the weight on a standard 5ver hitch spread out over the total top of the 5ver. So once those set screws cause a deflection in the flat on the pin box the metal will warp...common sense to me but hadn't thought of it that way until I read OPs post. The spacer will work as it is totally separate from the pin box and still spreading the weight out across the bottom of pin box and providing the material to take up space between the Andersen adapter and the pin box. As long as the bottom of the pin box is flat, the pull on the pin is in a horizontal plain, once the bottom warped your no longer pulling on a horizontal plain. I would replace the existing pin box though. Oh and thought I'd better say that I'm not defending Lippert as I know a lot of their stuff is possibly under par but I do kinda understand metal stess.
