Dog genetics Help!

I'm not on a high horse. Whenever you breed for a recessive trait, you need to be extremely careful to ensure you are not also getting recessive health issues.

And breeding an American Pitbull Terrier to an American Staffordshire Terrier IS crossbreeding. The puppies are not purebred.

You are contradicting yourself. You said:

Different breeds.

They are not the same breed, and responsible breeders breed to improve their breed, not for money.

So do many of the unwanted dogs that end up in kill shelters.

Which makes you a BYB.