I like that idea
Simple. Did you run down each side or just one side ?? For some reason I always thought silicone sealer and steel like that were a no-no that the silicone would corrode the metal and that rtv was a better choice.
Another method is to use amphenol bulkhead connectors. You see them on alot of military vehicles for connecting up radios, nbc detectors, etc. They offer a fast way to remove the rack w/lights still installed and they have a cap that seals the bulkhead connector when not in use.
They come unassembled and in a variety of configurations and wire counts. You do need to drill a pretty big hole in the roof or other area where you plan on putting it, usually 1/2 up to 1" depending on the wire count.