Id sugest maxclarity MaxClarity Foam - Get Clear Skin from the Only Acne Treatment with Foam
to get rid of the issue with the lense.

Coating the headlight is dumb in my book and retains heat which could indicate your problem. Borrow or steal or buy a IR gun and measure the headlight area to see the heat at the plastic, they are good to like 145 degrees F so your doing something bad there tiger. Woody Enjoy

The PROJECTORS have a 3" lense that could be focusing the thermal energy into that spot, so have a look or touch it to see if it is like HOT coffee.