I decided to try something I did long ago in college, back when I was doing intaglio printmaking. There's a technique called Chine-collé where you take some lightweight paper (like fancy Japanese rice papers) and bond it to a heavier surface for support.
I dug up some rice paper I bought a long time ago when my husband wanted me to teach him traditional Chinese brushwork. It's light, very porous, and extremely absorbent. I traced and refined my sketch on the rice paper.
I then took my canvas and with a wide flat brush applied a layer of watercolor ground over the whole surface.
While everything was still wet, I laid my rice paper sketch directly into the watercolor ground, making sure there were no air bubbles. I gently wet the upper surface. Can't brush it because the moistened rice paper was so delicate it tore and wrinkled very easily.
I let it dry overnight, and was very happy with the way the rice paper had adhered. I then took transparent watercolor ground (I've only used the White before. This is my first time using the Transparent) and painted a thick layer over the top of everything. This is where I am currently, letting that layer dry. I'll be applying another layer, and then sanding it smooth before painting.
Here's a smaller mini 3x3 inch canvas where I followed the same steps as I did on the larger canvas, in parallel. It's my test, to see how the paint will sit on the final surface. I only did one layer of ground on top of the rice paper for this small one, and There is a lot of absorbancy of the pigment, I think because the rice paper might still be exposed a little too much. But in general I'm pleased with how it's working out. I think the secondary layer of ground on my larger piece will fix any excess absorbancy.