The original poster asked if there were any washtub bass players "out there". Well, to a lot of folks, all washtub bass players are "out there"! No, seriously, if the bass has a lever, then the lever either already has, or can be provided with, an attachment which will indicate the lever position, thereby making it easier to "almost hit" those notes. Now you need a washboard percussionist, and a cigar box guitar player.