Welcome to the forum.

You won't be glueing any glass onto the DOT lamps, that's for sure.

The option is to convert to Euro lamps and eliminate the plastic completely.

The costs are variable from about $600. for brand new Bosch to $150 or so from a parts car with the associated deterioration of the lenses.

I went in the middle of the pack for the '86 and got a set from these folks.........$205. and they come with the clear corners:

http://www.importvision.com/index.php?display=show_part.php&PartMake=Mercedes&select_PartType=Headlights