There isn't only one way to go when pulling hidden traits, so I'll share the one that I personally like (learned from Liriel at her Kitty Kottage classes, but expressed as I interpret it, so any complaints should be directed at me
).
Your kitten needs to toss his/her hidden tail and won't do it for every box, so you need a more recessive tail to be able to tell whether the hidden has been passed or not. However, your kitty is still hiding perfect eyes, which I think you said you'd like your kitties to have, and is showing no whiskers shape. So perhaps it'd be a good idea to choose a more recessive tail that is not too recessive, so that you have some room to breed out those 3 traits. Once you have those traits showing (it may take more than one generation, that's why you're leaving room to try with a yet more recessive tail if you need to) , you can breed siblings that you know are hiding the chopchop or more recessive and wait for a "double pull" , ie when both siblings toss their hidden in the same box. If you have siblings that are showing different tails but both hiding for sure the chopchop (+), it'll be easier to tell if one of them has passed it and then that box can still be useful for your project. The different tails may come from the other parent tossing their hidden (provided it's more dominant than chopchop) or by choosing half-siblings. If you knew for sure the hidden is Chopchop, you could also use an unrelated kitty that you know is hiding chopchop.
I'm not experienced enough to say how you can do that and keep the fur you have, however. Perhaps hiding it under a fur that's more dominant than Snowshoe red, but where the hidden fur is more recessive than snowshoe red and more dominant than Bali Seal, and then pulling the red back out. It's something I'm still wondering about my own projects, I'm afraid.
