That's exactly what I did (well, same concept but a little shorter).
Rear remote levers on my Bobcat CT are stubby little things on a pedestal to the right of seat.
Too short to operate with any finesse.
They're round bar 3/16" or so with a plastic cap.
Removed the cap, threaded the ends and added a piece of 3/16 threaded rod and coupling to each. Cover back over the new end.
Think I added about 10" or so and it's a little too much but just haven't gotten around to cutting.
MUCH easier to control now and well worth the effort and minimal expense.