Sadly, Scamp does not wire appliances that weren't ordered with the trailer, so the wires won't be there. As suggested by Pine Cone Don a long time ago, Casita
owners can see the exact path of the wiring by shining a strong light
down from outside at night, kinda like candling an egg
What I did on my Scamp was use a small electrician's fish tape to push a tunnel thru the Reflectix bubbles between the ratfur and fiberglass and bring it inside the overhead cabinet (wedged free a bit with a screwdriver) to pick up the lighting
wires that run thru the cabinet under tape. An alternative is to put the wire outside the ratfur and cover it with some Velcro.
Be sure to allow plenty of excess ratfur for trim on the fan hole...