I don't know about Forest River but I used the skylight in the bathroom as reference to get behind the shower wall. The plumbing wall goes straight to the basement.
Don
Sent from my iPad using Forest River Forums
__________________
2014 Cedar Creek 36CKTS 2012 Dodge Ram 3500 LARAMIE
I think the most important to me was taking the shortest possible route from my panels to the controller/battery bank. I ended up just drilling though and passing the wiring down through the hollow sections of the entertainment center. Of course that is where I placed my conduit and c-box so it all worked out well.
If the reefer vent is the most convenient and en route to your controller then I would say go for it. Just ensure the wiring is properly protected on the way down.