Technically the main reason for taping the lights is to keep glass off the track
when your lights crack or break.
I don't think the tape actually protects them from breakage much. But, it definitely protects from the "sandblast" effect and little chips.
Last time I had my 70E on the track, I removed the foglights, put plastic Hella covers over the driving lights, and taped the headlights. On the 914 I routinely taped the foglights (headlights are no worry on those cars!)
You probably want to get a roll of "racer's tape", or borrow some from somebody at the event. It is very similar to duct tape but comes in colors other then grey/silver and also does not seem to be so "gummy". It is very easily removeable with little or no glue residue left on the car.
Have fun!
