I don't care for it being roof mounted. Seems the cords would always be in the way. Your best bets would be one 4 port by the nightstand, a 1 or 2 port in each bunk (if it has bunks equipped) and then another 4 port near the entertainment centre (for powering ipods, etc that might be streaming audio/video.) You can put the net kind of behind the TV to hold them up while making use of dead wall space.
The only reason I can think of for wanting it to reach the dinette/sofa would be for the kids to have power while in transit. In that case, you're probably better off looking for an under seat solution where the kids can pull power from the fascia of the dinette booth, or somewhere around the sofa, depending on which has the seatbelts.
There's no use crying over spilled milk, unless it's on your keyboard.