The biggest problem isn't the demonstrators it's les casseurs. I don't know if this could be adapted by the French Police. But I saw the Israelis, (military?) what they do against the Palestinians:
When they are demonstrating or flying burning kites etc. They send in a group of Israelis dressed the same as those demonstrating, causing havoc. They all have their faces covered so that they can't be recognized - the same as in Paris- Then they spot the ring leaders and then grab them. The Israeli army then break cover and they make off with the ring leaders.
If the french police could adapt that style of tactics, as soon as one of those little c*nts pulled out a spray can they could bang his head against the Arc de Triumph and hand him over to the the CRS.
Of course you will have people complaining against Police brutality, they would just have to deny that they were police officers.