Hmm, sounds like you want a light without any fixtures. Then how about a single long piece of LED lighting strip that's waterproof and submersible? They sell it by the roll. The LED strip could be immersed in water just inside the top front rim, facing inward/downward? Perhaps even permanently siliconed into place. Then all you'd see is a single power wire that can be easily hidden by the trim. A wad of silicone over the LED-to-wire connection(s) would render it waterproof too.