Would it be possible to elongate the lower horizontal arm of NN5 approximately 6"?

In order to photograph the nadir from exactly the same distance from the floor as other shots, one could shoot the horizontal shots, the zenith, then reverse the Vertical arm 180 degrees and extend it away from the tripod maximally while pointing the camera downward 90 degrees. One would have to move the tripod and center the lens over the nadir center point of course.

Currently the lower horizontal arm is not long enough to achieve the desired results with this method.