Hi Vernie,
I think the choose of the right marker also depends of the method how you are going to do your wholecloth. When you quilt in a big frame you can do the markings before the layering - the marked lines do not rub off so easily. When you are going to quilt in a hoop you move your quilt a lot and the markings can come off quickly - so it would be better to look for a more permanent marker or to mark "as you go". "Mark as I go" is the method I prefer, therefore I can use the method of needlemarking with a darning needle on light fabrics(the traditional method you find in Mavis Fitzrandolph's book - could you find it somewhere in a second-hand book store?). My choice for darker fabrics are watercolor pencils. They are available in many colors and I always look for one that is a few shades lighter than the fabric (or the quilting thread). I also tested the Bohin marker Sharon Schamber recommends in her video and as well the Sewline - they both work fine.