Doesn't that cause a potential water ingress point from the snorkel?
I have a roll bar style light bar with 2 side firing lights, 4 spots, 2 fogs, CB coaxial cable, centre point cable and FM aerial cable. All the cables go through the bar itself which bolts to the roof. I have all the cable running through a 36mm hole in the roof which is well sealed using marine sealant.
I had looked at all the possibilities whilst figuring out this question on a friends Landy before fitting mine and found several marine cable inlets which could do it. Some are sockets so you could remove the light bar/roof bar and still leave it waterproof.
Sorry, should have been more descriptive. The wire is cable tied to snorkel, goes into the engine bay at the back of the bonnet then in through the bulkhead through a rubber grommet.