OP: Now that your have a vent and fan...
* Have you considered adding 2-4 new recessed LED light holes on either side of the fan box?
* I'm sure it would not be hard to run power and ground though the styrofoam to reach the recessed light holes if they are positioned ~1-foot from the fan box?
If you go this route, please post some more pictures for the rest of us to consider, and thanks for posting pictures of your fan/vent. It looks great!
Note: The wall switch only has 1 power wire, but I'm sure you can add a toggle power switch in the fan box... that when flipped to position 1 would only turn on the light; and in position 2 would turn on both the light and the fan from the wall switch.
2004 Itasca Horizon ISK-40AD, 350HP Cummins 8.3L
115K miles and the best of 3 Diesels I have owned thus far!