I just pulled this from the Supply List on DMP which will update Mark's recommendations for you. Mark experienced a dreadful event with the Claessen's double-primed #13 and changed his recommendations in an Announcement. I can't seem to find that thread.
"canvas & stretcher strips
If you buy pre-stretched canvas, I recommend Centurion brand primed linen canvas.
If you're going to be stretching your own — which I demonstrate here: youtu.be/5Aw820hyZS0 — you'll need to buy canvas and stretcher strips."
I know exactly what you mean when you say that customers expect artists to use traditional canvas. I've experienced that myself. In fact, switching to composite aluminum and creating my own floater frames is much more archival than I could have ever hoped for with canvas but the nostalgia isn't there and I miss that. I will still use canvas now and then because it is more romantic to paint on. Claessen's Belgian linen # 13 is also my favorite.
I hope you will let us know the outcomes of the things you will be trying.