If you feel the need for drift lines and don't want to clutter your map, then get a strip of acetate or clear plastic and a sharpy pen and draw a pair of lines intersecting at 10 degrees.
When you have marked a position fix on your map, drop over the overlay and interpolate your track error and/or closing angle.
Alternative is to ignore them completely and use a standard closing angle technique. I know that you still want to know the track error to set the new heading required.
Better still, use a GPS and don't get off track in the first place. But that's after you finish your training
