You really need to approach the career CFIs- the CFI demographic in the US is predominantly young and male, precisely the group that tends not to vote according to the political scientists. This group has weak collective awareness and they do not vote much or tend to act for collective goals. They are not old enough to have developed the kind of collective awareness needed to permit forking over dues to a union. But if you could get the attention of the older ones, it might be something they are interested in.