To keep from scratching up the back of my basses, I've used 8"x8" squares of moleskin(Foot dept. in the drrug store). Put it on the back, it lasts almost forever. The gig I'm doing now requires a cummerbun, so it's no problem. The only reason I worry about that any way is to keep moisture from getting to the wood. Most 'character marks' can be covered with water based urethane. Seals it and not noticeable.