That would be some STC! The push/pull tubes for the MR and tail rotor control are housed in the "closet".
You're right, of course. It'd be very hard. I was thinking along the lines of a 'fly by wire' control unit that gathers up info from the cyclic, collective, pedals then passes it via an optic fibre onto another box on the roof that moves the actuators, then to the tail to control the TR pitch links.
Bell just keeps making machines that looks like their old Jet Rangers then wonder why EC, Agusta, Robinsons all steal their market share.