Maybe a narrow strip of material on the waistcoat (if the waistcoat is black even easier) sewn on one side and open on the other so the buttons are covered but you can still button it?
Couldn’t one of these be the solution for those BC members who often see an instrument and say “If that only weighed 3 lbs, my poor back“ etc? Then it wouldn’t matter if it weighed 20 lbs.