I hesitate to actually believe Lippert frames (or any for that matter) are "engineered" to any large degree. I'm sure they must have someone with a spec or two of knowledge about structural design and stress designing these frames. The truth, however, might give us pause.
That said, I'm not sure I'd be comfortable throwing in extra support willy-nilly because I believed it would be better. True, I have built and repaired many things in my career that have held up quite well, but I'm not an engineer and don't play one tv. When you add bracing that wasn't there to begin with, you change how the frame moves and supports. Unless you know for relative certain that is in your best interest, you may be making a bad situation worse in another area of frame by shifting stress to another point which isn't up to the task of taking it. Word to the wise.