If you want to try cutting the rear legs you may be able to cut just beneath the hips (I know it sounds gross, but sometimes I have to modify diet for the wild animals I help care for, and we try everything from skinning, to cutting into pieces, etc). If you cut beneath the hips the guts won't come out, although I'm not sure it will make your snake feel comfortable enough. It almost sounds to me like the feeders are too big, but you insist they are not. Maybe try tangling the rat by the tail? I always feed this way so my snakes grab the head or upper torso first, then follow through after they are done constricting. I know you posted your snake's weight; can you post a pic?