I believe the depth of the centerboard on the TI is close to the depth of the mirage drives.. but have not carefully measured this. FYI, if you ground the CB, it will pop up on its own so no big deal.
For the centerboard control from the rear seat, I use a very simple mod to one end of the paddle which I carry with regardless. To pull the CB down, I just get the loop around the knob and pull it back. The length of the loop line has to be long enough to easily release from the knob. To push the CB up, just use the end of the paddle (same side as the loop) and push the CB forward. I really cant tell the mod is there when Im actually using the paddle.. but then mainly use the mirage drive to get around.
I have been using the paddle this way for a long time and think it works nice for how simple and light weight this is. Pictures are hosted on FB so will go away in a while.