There are tons of sand/tan/beige colored batiks available, but I don't know if they come as pre-cut strips. Is that critical to you for some reason? Try Hancock's of Paducah and search their batiks by color.
Your quilt idea sounds like a real winner. My daughter also rides (and judges) dressage. She learned how to quilt just so she could make her own schooling pads and blankets.