I think we're all assuming that you are planning on playing a quick set of progressions to transition from one piece to the next?
You wouldn't want tp pivot on C because it is not the dominant of the new key, which is what is important. If you play a CM chord, the ear wants it to resolve back to f-, not GM. This is where greyrune's D7 comes in, to establish the new tonality of GM. Another possiblity, if you don't opt for the secondary dominant, is to use a secondary leading, as in fm > CM > f#half dim. > GM.