You can try One Grand PLASTIC POLISH & CONDITIONER on the bug deflector. I used it with good results on my long since sold GMC 3/4 ton's bug deflector. Not crazy about the smell but it worked. Also, used it on the old E36's plastic headlight covers to remove dried on bug carcasses and swirl marks from the previous owners.
I still have some around, if you want to drive out to Cochrane.