Advertising on the Paris Metro

We are a music group trying to buy ads in the Paris Metro, although open to other ideas.  The band has had some recognition in the states over the years, but has never tapped its potential in France—strange as the band was first produced by Mylène Farmer.  We are hoping to change our visibility in France. Here is some context:

While the music is quite commercial, it can lay claim to a strong literary foundation as songs are also created around the ideas of Oulipo, Pérec, Proust and Villon.  The songs are built to not sound academic however, and are geared for a mainstream pop audience.  Here is an example “Between Clenched Teeth”, a song without vowels A, I, O, or U.

We would like to do some heavy promotion in the Paris metro, think we might be able to make a “culture” claim etc (discount? extra eligibility?), but are not sure what urls or channels to go through.

We found this street marketing company but this seems to be a middleman—ideally, we would love a direct contact to the RATP to talk terms.  The RATP seems to have no contact or link for advertising—only a link about its advertising *policy*.  Perhaps that is not how it is done, however?

Also, do we need to form a business entity in France to buy these ads or can we operate from the states?  Happy to do so if need be, just don’t want to create anything unnecessary.  Perhaps it would help us down the line?

I looked through the other questions and found one marketing question answered for a language school, but did not find exactly what I was looking for.  Happy to be directed if I missed a post.

So grateful for your help, sorry if this is too long or wrongly formatted, this is SUCH a great resource!

Mulipo