Honestly as someone who's done le mans before. Don't think about punting. Enjoy it for what it is, the cars, the sounds, the smells and the utter piss up. And even better. If you know the right folk, you'll get access to some people and places there that you usually dont
Punting in France is pricey, it's illegal. Try your luck on Civvy street.
What I will say however. When I wasn't there for the 24. There was definitely some less savoury types on the Avenue De La Liberation hanging about. Street walker vibes