Securing the key in timed chastity devices

Taking the CB6000 as an example, how do you secure the key so that it remains inaccessible until a set period has passed? I’m aware of at least a couple approaches, though each has drawbacks:

1. Sending the key back to yourself. Wouldn’t this typically reach you within one or two days max? There’s also the slight risk of postal loss, even if uncommon. A typo in the address could cause it to go astray.
2. Placing the key inside a container and securing that with a combination lock. You’d use software or an online service to manage the code. The challenge lies in finding the right box; I haven’t done much woodworking or metalwork at home, so suitable boxes are hard to come by locally.
3. Locking the chastity device directly via its built-in loop using a combo lock. This is usually tricky because the hole for the padlock shackle is quite narrow. Additionally, some combination locks are bulky and heavy. To solve the small-hole issue, I could use a thin metal wire looped through the opening to secure both ends of the shackle. The difficulty there is sourcing such fine wire.

So theoretically, option 2 seems best for now. Any suggestions or thoughts on these methods?