I wish you luck with this. I made a Hopi Sun Quilt in the round using a 10 degree wedge. It didn't just take one ruler, it took THREE. I had to place two more long rulers along both sides of the wedge ruler to keep the cut true and the fabric stabilized.
This was made in a class at G Street Fabrics. We made large stripped pieces to cut these wedges out of on an angle. This left lots of waste. I am just an old "covers" quilter in love with straight stitching. I won't take this on again. But my DH loves this quilt!
Good Luck and I hope you enjoy this process more than I. Each to his own as the old lady said when she kissed the cow!