I used to be a ski technician many years ago. Used to run ski/board over a machine with a wide belt sander to take out any 'feathers'. Carefully clean, scrape and cut grooves in damaged section with stanley knife if needed. (This is probably more needed on snow.) like surfboards the worst to repair are those long dints that just tail off; deeper gouges hold material better. We had like a big hot glue gun that filled and spread at same time. Then run it over coarse or fine belt sanding machine again, depending on how damaged edges were. Repairs generally only needed a light sand. They were mostly invisible when finished And waxed. In Australian snow conditions, we were kept very busy by punters, let alone the rental gear. Maybe something similar there you can use.