MeudtPG, I just purchased the exact same from Amazon, but have not yet installed on my 2018 RT as it will require a little cutting......and I did not have an answer on wiring it up anyway.
That said, I did pull the blanks. The center blank on the 2018 uses a round hole.....the entire shape would need to be cutout for the USB. All of the blanks EXCEPT the center are precut rectangles roughly the size of the USB with two caveats. First, the slots on mine seemed just too narrow/small, but barely.....would either be a very tight fit, or it might need slight enlargement with a file etc. More important, the blanks in the bike are pure rectangles. The USB/Switch is a rectangle with a small "dog ear" on the top and bottom. The "dog ear" is square in nature, and is used for the clips that hold the USB in. You would have to cut these "dog ears" at a minimum.....you might be able to use a good file, or even a knife. Would be minimal cutting but you will have to do some. I BELIEVE this true of all of this type switch/device, everyone I've seen had the dog ears.
If you go to pull one, suggest removing the center first as it is much easier to get out. From there, you can reach under and try to push in on the clips for the outer blanks. Still a little work, but will come off much easier if you can at lest help from the center hole.
As a note, I had mine apart mainly to install a garage door opener that uses one of that style switch -- matches perfectly. If you are going to do a garage door opener install at some point, would be easiest to do at the same time. I used a "mo-door" that came with the RT switch, a little expensive, but installed and works VERY well and at much better range than my Honda and Mercedes Homelinks. The mo-door switch even used a perfectly rectangular switch with no ears, fit perfectly.
