Implementation of a "Tail Toggle"

[Quoyan]

Miqo'te Tails don't stick straight out, they point downward. If a costume has even the tiniest bit of extra space in the butt area, you can maneuver the tail after a certain point down one leg of the costume.

If your argument against hiding tails with certain gear, such as the Chocobo Suit, is that Miqo'te tails are shaped incorrectly to be hidden that way

That's not my argument. Physically it would be possible, however Miqo'te are cat-like people. That tail is an extension of their spine and is essential for their balance. They'd be extremely uncomfortable (and noticeably more clumsy) if they stuffed their tail down a leg or something.
Try sticking your spine down the leg of your jeans later on and tell me how you like it :')