On the hatch/vent installation, I decided that becuase I was mounting mine pretty far aft, that I could sacrafice one beam in the ceiling. I did run "L" channel from the beam to beam to support the new opening. It has worked out well. I was just on my roof yesterday to wash it (man was it dirty) and it all seems to be holding up well. It does not flex at all, so I guess adding the channels really helped. It did feel funny cutting a hole in the top of my truck. These things are built like tanks!
Dodger
I posted pics of my vent installation in my "Productive Weekend" topic
Thanks. That's actually [sort of] the same route I took. One side was already braced from the factory, the other I plan to run either a piece of angle or box tube underneath to shore it up, but we'll get to that after this weekend's camp trip.