Hi Mate. I have a clearer head today
. No Jacks and cola for Monday mornings.
My suggestion was much the same as AndreZA mentioned.
I dont know your capabilities. But for the beginners, I would always say, Learn it all. And others that have had more experience with Canvas with out Geusso priming may just have "worked" out a smarter method that also works. Or that works for them.
Another idea, I had, but only tried many years ago. was to lay tape or Cantact (like a school grade vinyl) over my Paper stencils. They have a little more durability from the wetting. They will curl when dry. But thats better then Buckling.
Forgot to add. Your uneven surface (Canvas). Try some of these tips. Lower your PSI. When spraying over your Stencils, Point your nozzle away from your stencils edge. So blowing your mist on the the canvas. Never paint onto the stencils at a 90deg angle or you may find (oftern then not) overspray bleeding off your stencil marks.
Dan