Use something medium. The other guys are going to be blowing a hole in the long pattern because they're going to see 47 feet and freak out. There's going to be Scotch Brite and charcoal in great amounts. Use something with medium diff, medium RG, and 2000 grit doesn't sound like a bad idea. That way, when a hole blows open (and it will, trust me), you will be able to stay out of trouble.