WOW, I can't believe none of the above mentioned would get a pen mark off of the coated canvas?! I thought that was the one HUGE benefit of the coated canvas...EASY CLEAN-UP! I wouldn't have even been that worried over it when it happened but after reading this I don't know how much I'd invest in one!! I've been thinking they'd be great for winter with slush and all, but who know's?!
Back to your subject......if it makes you feel ANY better I cleaned a regular signature kahki Carly with the magic eraser and it ROCK's!!! The bag was in AWFUL shape when I got it, soap and water helped but the magic eraser was a total HOME RUN!!!
Best of luck hun, we are all "keeping our fingers crossed" for ya!!!!