Jim, that decal is a hoot! How new is your tractor, and could you describe more specifically where on the underside it's located?
Curious, was it a dealer that said they couldn't install a third rear remote, or did you hear that from Kioti corporate? If the latter, wow, they need to update customer service. Although there technically isn't a "third rear remote kit" offered in the U.S., all that's needed is an additional No. 2 valve body kit, and two longer bolts because of the added thickness: 10-1.25 x 170mm, ideally grade 8.8 or better. Fastenal has them. BTW, my dealer in Mineral, VA did this for me last July when my three-year-old NX was in to have an ECU programming update and a couple of other things.
If Kioti corporate in Wendell is still not recommending using the No. 2 kit as a third remote, maybe it's because the lever will be color-coded (blue) the same as the existing No. 2 lever, rather than green. That's a non-issue, as a practical matter. There is already plenty of room on the stack for a third valve body, as well as a cutout for the cable and a slot for the third lever already in the control console.
BTW, I've heard that a dedicated third remote kit has been available outside of North American for quite a while.