........... I just use a long sanding bar 18in with 80 grit sandpaper glued to it . Then just by feel and eyeball..........

Pretty much the same way I do it. I have a small finger plane that I use to do the rough shaping, bringing the upper and lower surfaces close, then try to draw a centerline on the L.E. with a felt marker and work to that. I make up sanding blocks out of pine and contact sandpaper to them. they work well. For final sanding I usually curve a piece and use my palm across the front.
Randy