You could try a brighter bulb but risk melting the lense/fixture. I had that problem with the little light over the sliding doors. The fixture melted. I think the transom light fixture is stainless but the lends may get damaged.
All the talk about LEDs has my interest. I have had the worst luck with those festoon bulbs. The glue on the end caps seems to dry out and the caps come loose causing random bulb failure.
-Karl
1986, 32' Sedan, twin 360ci, 275hp Chrysler's w/ K&N flame arrestors