[erebus]

latex/nitrile/vinyl gloves, acetone and some elbow grease.
Gets the residue off pretty quick. Maybe some goof off to change it up if you like.

Also, a painter years ago taught me a trick about using a sharpened piece of plexiglass/lexan to scrape off old adhesives/vinyl lettering etc.
Cuts the goop off but wont scratch the gelcoat. Then clean up whats left with the chemicals and elbow grease.
Sometimes the non-skid can make it tricky, just bear with it.