I had the same problem with moisture in the Headlights.
Got two small bags of Silica Gel, the stuff that comes in the box when you buy something New.
Place one in each of the snap on covers that cover the Bulbs, snapped the covers back on.
NO more moisture !!!!.
IF it comes back, I will take the Silica bags out and dry them, then pop them back in !!.
Worked a treat, dead easy to do too.