Have not gotten the projectors yet, but I wanted to play around and see how I would seal up the back of the headlight so moisture does not come into contact with the projector bowl (which will stick out the back). Found this at home depot, and it looks like it will do the job well. May have to shorten it a bit because the projector should not stick out that far. The stock bulb seal fits on the end
I checked the fit against the headlight, and the PVC will need a bit of trimming to fit properly, and it does not have to be as long as it is. Other than that, looks like it will work.
EDIT: Ended up not needing these!