You may need/want to replace the Taillight "Cover" also, from Slash to non-Slash. #7 above, part number is 5458140. Cost is ~$15USD. If you don't you'll be cutting your Slash cover; haven't laid eyes on the non-Slash flap, yet, but got a hunch it gets supported by this non-Slash cover.
Same tail light, Slash - non-Slash. Same Tail - Tunnel, Slash - non-Slash. Looks easy right now. The short tracks use a different flap - make sure you get the RMK/Khaos flap ID'ed above.
Get the cover and flap, and swapping covers/flaps during the season could be as easy as four bolts/nuts, maybe nutserts, if you don't want to rivet. Not done on the hill, but maybe spring vs. real winter.