This is a great add on. Specifically for Coyote Trail, I've always liked the idea from Deadlands of using a poker deck and chips for some easy game mechanics to give a little more genre immersion, but I hadn't settled on how to implement the ideas with CT. This looks cool and will definitely go into the options playtest queue for our game.
One thought though, what about letting the player apply a joker to play the primary card on another character, as written, but let them invert the bonus into a penalty to use against a villain or antagonist NPC? Since there's only two jokers available for the entire session, it shouldn't unbalance things too much, and could create one of those big cinematic moments a western game is built for if the player waits till a climactic moment to drop a penalty on the bad guy.