Yeah.
Even though it seems unrealistic, I do admire the thought of protecting your snakes. I think you should still pursue your breeding goals.
Maybe try to find an alternative for sterilization?
Verbally explain to the new owners that the desert girls cannot be bred. Send them home with a written caresheet.
And as I said before, a legal contract for them to sign that states that they cannot breed their animal. Dog and cat breeders do this, so why not you and your snakes?
Maybe rehome them to educational programs instead of civilian homes. Or even zoos and wildlife centers. I know you are in Germany, so I'm not sure how things work there.