How are you guys doing this? Hole in the roof and silicone? I'm thinking about running the wiring along the windshield moulding. I would prefer to not put a hole in the roof and dropping the headliner if I don't have to. Thanks for any input!
I've been thinking of how I'm going to do this on my hilux. I think I will opt for a neat waterproof gland in the centre rear of the roof. You won't see it as you stand next to the vehicle, it's easily sealed back up if you ever decide to remove your cabling and you can just feed the cabling down the inside of the rear cab plastics to wherever you need to go.
I've seen this done on emergency service vehicles for years.
Don't use silicon; if you are going to drill you might as well use a proper cable pass through (marine use ones are sometimes called cable clams or deck seals ex. http://www.defender.com/category.jsp?path=-1%7C328%7C2289986&id=2289996). If you want to use a sealant, use something like 3M's 5200. Silicon is very difficult to properly clean and reapply if you should ever need to.
I have a 3rd gen 4Runner. I ran the wiring to the passenger rear and passed it between the hatch and d-pillar and drilled a hole in the bottom of the d-pillar by the weather strip to pass wiring into the quarter panel.