Your guesses make for a good starting point.
I'd get up in the attic with a bunch of blue paper towels. Take the panels on both sides of the attic down - you don't have to remove them or disconnect any of the wires. Lay and/or tape the blue paper towels near/on the areas that you suspect (i.e. around the "Oliver" sign, around the hole into the main cabin, in the area of the rear view camera, as far as you can reach towards the a/c, etc.). Go outside and give this area a good soak with the garden hose. Go back inside to look for "dark" spots on the blue paper towels which will give you an indication as to where the leak is coming from.
Good luck!
Bill