Background: D-Tuna is a device developed by Eddie Van Halen that sits on the screw of your 6th string that drops one step in the tuning of that string quickly (according to a few videos I've seen on YouTube, it takes about a second to reach out for it and make the change - if your bridge is already locked).
It does need the bridge to be "locked" (using a separate device such as a Tremol-no or Tremsetter) so that the variation in the total pull force from the strings that happens when you change the tuning using the device doesn't change the balance of the bridge, and effectively detunes the whole guitar.
PS: for the sake of the question, assume that the device is present, but you don't want to use it for a particular song, and that whatever bridge stabilizer you have in place is not active. Does the physical presence of the device limit the range of the bridge?