Craigs list is not the universe.
Bottom line: Be as honest as you can. If your rating is not official, just say that.
Sorry to be such a stickler, but there is enough misinformation and kvetching about sandbagging etc without having people muddy the waters more by saying they are 4.0 when it is based on what their pro told them, or the country club rating conversion chart, or a home grown algorithm.
-- Random Error Generator, Version 4.0
-- Master Moonballer