I have a 'million" questions regarding the TFI but that's another subject I'll take up with the boys from Dobeck directly.
I also have the same issue with mounting the TFI. There is very limited space to mount anything on the FLSTC, especially mine. I have another accessory under the seat that takes up all available space. I have the tail light/brake flasher/turn signal conversion kit there. The ECM on the FLSTC is mounted in a slight recess in the rear fender under the seat.
I agree with GroundHawg that space is truly "the final Frontier" when it comes to the Heritage. Essentially, there isn't any space. And the Heritage doesn't have side covers. We have oil tanks instead.
So where can we mount the TFI with the consideration that the device should be accessible for adjustments rather than hide it behind the fender panel? Not a very convenient location.