Annexe walls

I already have a bag awning on our poptop camper, and are in the process of getting the walls made up now. The awning was made out of PVC so we now have no choice about the roof, but what is better for the walls?
We have the design that all 3 walls will basically be zipped down to bare mozzie mesh if we need the airflow.
I am leaning towards the canvas for it's ability to breath, but will this be important if we zipped all the sides down anyway.
I've noted that the PVC will gather condensation, but having the roof allready PVC don't have a choice on that, will the walls play a part in dripping condensation then?

So considering the roof as PVC, what would be best for walls??
Thanks agian
Troy