Personally, I would invest in a crate. : ) They are very helpful, for LIFE! You can buy a medium/large crate (depending on his breeds), and section off part of it for him until he's full grown.

The key to ending the crying is not enforcing it... don't say a word, don't even look at him.

How does an 8 foot leash prevent him from having accidents? Couldn't he just walk to the end of the leash and pee, then go back to his blanket?