Couple questions for you epoxy/tow in guys

I made a board for my uncle to ride in the gulf (slow rolling mush waves) and it was a sanded white finish. The board was a sanded white tinted finish and turned out to be too small for him so I took it back and made him something bigger…

First question… somehow the board seems to pick up dirt like crazy… theres black hand prints and dark spots where it seems the sanded finish just likes to soak up the color from anything that rubs up against it. Is there anyway I can clean the epoxy without having to sand it to get this crap off? If I can I plan on getting the coloring off of it and sealing it with something so it doesnt happen again.

Second question… for those who have made tow in boards / experience with them, there is an island off a local chain that gets good break but can only be accessed by boat or jet ski. We always take the jet skis out there and jump the waves but I was thinking last time how cool it would be to make a tow board to have fun with since no one is out there. This board seems to be perfect becuase its mildly thin, has a low tucked rail and a pretty flat rocker out the tail. The only concern I have was the tail is pretty wide since I made it for mushy waves (14.5 inches), will this cause any problems for drag or make it too slow to tow with?

Any help would be great