At the moment, there's very little we can do about the height of the
click-box. In fact, the only parts of that clickable frame that we
can safely change (with restrictions) are the height and width.
Adjusting the height will effectively raise the maximum vertical
position of the clickbox. However, since the nameplate is anchored in
the center of the frame, increasing the height also makes the frame
grow downward, which can make for some interesting problems of
overlap. To top it off, we can't change that frame's size during
combat (btw - the threat scaling feature merely scales the artwork),
since it's a protected frame.
The deck is stacked against us, eh?