I purchased the kit and installed it even though I never had any leaks or condensation problems. I did see one Crossfire that had so much water in the headlight that he could have taken his pet goldfish for a drive, as the water was splashing about in his headlight.
If you have a slight condensation problem then I would say use one of the old vents and plug the other one in the unit with a permanent seal. I think there is two vents in each unit if my memory serves me correctly. The unit must breath as the air is heated by the bulb and expands. Use the original large seals, I think this would work. I think the kit has one large seal that you install and it lets air pass through both ways through a very fine mesh, water may not be able to pass through this mesh. Maybe water vapor does not pass through this mesh. If that is so find some of this material and glue a patch to the large seal.
If you have a leak, fix it.