For a taught enough connection to flick the bell, seems like you’d need to move the bell from the stem onto the frame somewhere - maybe where the FD would mount. Otherwise, you’d need some sort of connection that allows for the stem rotation. Would it work to go ahead and mount the bell upside down in the FD location and just route a cable from the lever back up to the right shifter with enough tension so you could just flick the shifter lever to ring the bell.
Good luck, I had fun rigging dummy thumb shifters (concealing the rapid fire shifters) to cheat my way to Cino stamp last year.
