I would hold off on the desiccant unless really needed. It seems like it occurs mostly on daily drivers with seam problems which are driven in the rain. The youtube fix? is to blow low pressure air into the headlight for a few minutes through the bulb hole thus removing the humid air that has accumulated inside the headlamp. The warmer the air blown in, the less time needed.
01
(my thinking on this problem is that hot air expands inside the headlight when lights are on. This breaks the seal of the unit. As the air cools, it pulls in the moisture where ever it can like rain or washing the car. Possible cure might be to drill a 1/4 inch hole at a location that is not visible (in the bottom?) and glue a cigarette filter in the hole. This would allow for the air expansion/contraction without pulling moisture into the light bucket) my $.02
Something to think about for sure. Im not sure the heat blows the seams in the OEM headlights as the OEM headlights have drains in them.
there is a youtube video that states having the lights on causes the problem in the OEM lights.
I think the main thing I am thinking about when putting these together is how to get them apart if the lens get cloudy. With my removable bottom tub I can inspect the desiccant packets and replace if needed. They turn color as they fill up.
I'm not sure what the solution is and even Audi hasn't figured it out
I'm a ways from sealing mine up so I will have to ponder.....
Thanks for the comments 01!