I've been meaning to try something like this for a while. Colored pencils and marker on tan canson paper. It made more sense for me to work on tan paper since 90% of what I was drawing was going to be tan. The problem is finding a toned paper that is light enough so I can light table the image and transfer it through the paper. What really helped though was scanning the original pencils, bumping up the contrast, then printing the darker image on a thin paper. That way the light can pass easier through the toned paper and it is easier to see when transferring it on the light table.