Market stall registration?

I spoke to le placier for our town. I showed him my market Carte permettant l’exercise d’une activity ambulante that I had issued from the chambre de metries and asked how much it was to set up a stall for the day (€5.80). He suprised me with what he said next, that I need to write a letter to the Prefecture and ask for permission to sell in the market, once they have confirmed back in writing then I can go and see him and obtain a space.

Do you know if I need to go through this process for all towns that I want to run a stall for, example I’d like to start off in 2 other nearby towns, will I need to seek permission from the prefecture in both towns? Or will the main prefectures permission cover all of the markets in my departement (23) and all I need to do is visit the placier for these towns and ask for a space. Also if I want to go to another departement will I need to do this with that main administrative centre? Also when I write the letter to the prefecture can you give me some idea of what I should ask please, or is it that simple to say that I am a photographique artisan with this Siret No my name, my address etc. and ask for the permission.