This is how I modified my x52pro, it's pretty simple if it's just a straight extension.
Inside the base the stick portion of the gimbal is a metal shaft, I found that 3/16th stainless steel tube would slide inside of it. In my first attempt I used a cotter pin thru the two pieces to hold them together. This added a bit more slop to the center but it allowed me to experiment with a couple of configurations before finalizing a design. My next step will be to have the the shafts welded together but I'm still working on improving the spring tension adjustment to allow for more flexibility.