It's funny, I searched the web for a good definition of what a right to work state is. One of the hits was an AFL-CIO page, entitled Right to Work' States Are Really Restricted Rights States. The sidebar graphs basically can be summed up with "Women and Minorities Hit the Hardest". Same old tired arguments, from the same cast of characters.
Missouri will be a tough nut to crack. St.L/KC are pretty much unionized. I believe it to be worth the fight...
Essentially, a worker is not 'forced' to join a union or pay union dues even if the labor force of the working place is organized. Should more aptly be labelled 'Right to Choose'.