Pete, I have asked a similar question about a damaged support on my front water tank, and have since then learned enough to be dangerous on the subject, lol.
Not sure if yours is the same, but on mine, the outside end of the supports also ties into the running boards and works as a support for them. It is connected using 2 screws into the fiberglass. I would think if yours are un-naturally bowed, then this connection to the running boards would have gotten pulled away or at least loosened in such a way you can tell that its wrong.
Other than that, sorry, can't be a lot more help. Mike.