Well, considering the blocks are only 6" you're doing an outstanding job. What was the name of one of the blocks...........Rocky Road to Kansas? So a few bumps along the line isn't that bad is it?
I can't come up with anything else besides what you already mentioned. Chalk, pencils, I often use the grey/silver pencil but I find it hard to get rid of the lines in light colored fabrics. Chalk doesn't work for me as I'm quilting on my domestic and move the quilt around a lot. So I'm using frixion pens if any. Not much of a help, I know! Sorry!!