If you haven't fixed your problem yet you could take the circular bulb covers of and leave the car in the sun to allow the interior of the lights to dry out. Drop in a small pack of silica gel in the bottom of each holes and refit the covers. Keep an eye on the packs to check if they get damp. They can be dried out in a warm oven and reused. There are normally very small holes in the underside of the housings but they may not drain any water. You can run a line of sealant around the light. Bumper cover needs to come off or your car I think to remove the unit.
See TRQ video on the Tube.