I studied French for a year, and the general idea - grammatically - is that, if there is a male in the group, the group is referred to in the masculine gender. Even if you have a group of 1,000 females and one male, you're going to use masculine plural nouns and pronouns. So I'd say as long as you can assume there is at least one male in the group of {practitioners of parkour} you're referring to, it's just fine to say "traceurs". Don't take my word for it, because French isn't my best language, but I'm pretty sure that, according to French grammar, you're not excluding females when you say it that way. The only other option would be to go around saying "traceurs/traceuses".
But let me say an interesting thing about languages, some insight I've gained after spending several (otherwise pointless) years studying several of them...
(Apologise in advance for the ensuing run-on sentence)
Since the word, being borrowed from a foreign language and used only by a miniscule percentage of the total population, is therefore such a specialized unit of vocabulary (being used mostly - almost exclusively - by the parkour/freerunning community, ignoring use by the media, which usually only indicate that the word exists and don't actually use it in sentences), that means that we make the rules about the word's use in the English language by choosing for ourselves how we use the word. This also means that, until somebody can spot the word in a dictionary, or refer to its repeated and consistent use in major media and/or higher education, there really are no rules attached to the word, so it's up to each individual to use the word how they see fit, until a universal pattern arises, unless one has already.
