So I finally got around to calling Forest River and found out that the previous owner of my pup installed the AC unit in the WRONG PLACE!!
I guess that explains the slight sag in my roof. FR told me that there should be a small screw somewhere in the ceiling that denotes the location to be cut out for the AC and that there is framing and supports already in my roof. Thanks for the suggestion TexasBBQ
So I guess I'm going to spend my weekend moving the AC and (re)install a ceiling vent.