Othe ways to form a boule

Linen wicks moisture better than cotton.  Flour the boule and the linen, you can brush off the excess later.  Other people have mentioned a mix of white flour and rice flour.

I've had no luck with the mixing bowl and towel method, but I found that even my bannetons weren't stick-proof until I started using rice flour on them. Not sure if it would be a miracle cure for your sticking problem, but probably couldn't hurt to try it.

Besides the above suggestions you may want to consider a trip to the dollar store.  I found several baskets of different sizes I use instead of a banneton that I line with a towel dusted with rice flour.  Initial dusting of the towel may involve using more flour than you think is necessary, but once you get all the fibers filled with flour you should be able to use less in the future.

Whatever you do, just don't use brown rice flour. I did that once--great release, no sticking, but it was so abrasive that the finished loaf was like sandpaper, medium grit.

I got this idea from making pumpkin rolls. You spray and flour waxed paper and line the jelly roll pan with it. The wax paper holds the cake together so when it's done it's easier to handle. You flip it over onto a sugared towel holding it by the corners.

For the dough, I didn't bake with it, but it made it easier to handle the dough. I sprayed waxed paper with Pam then coated it with whole wheat flour. I placed the waxed paper in a casserole dish and left the dough there to rise. Then I picked it up by the edges of the waxed paper. I had to set it down on the counter in order to get my hand under the dough. Then I tucked back the corners of the waxed paper as much as I could and flipped the dough into a hot dutch oven. I greased the dutch oven first. I peeled off the waxed paper from the top of the dough then tilted the dutch oven to even out the dough. It worked great.