We do implant new gears every year for seasonal quests, however like Seth mentioned we also make the old ones available as well, usually with a small twist to it.
I'm not sure if making a new cart could be possible or not (i have to admit i'm not much of a scripter myself so i don't know the possibilities). I guess if i'd make it a sprite, it could works as equipt but i don't know about the rest xD However you did gave me some inspiration for some other Christmas related gears that may or may not be used in a future seasonal quest so i want to thank you for that