It sounds as though your dog really sees the crate as his safe haven. He is spending quite a lot of time in there, though as you mentioned, he does not seem to mind. Is he getting any exercise once you come home from work? Maybe you could take him for a walk around the block so that he is getting some fresh air and so that he is also being exposed to the outside world.
It's great that your dog knows not to relieve himself in his crate. I wonder if he also knows that going anywhere else inside is a no-no? You could try testing this, or reinforcing it by preventing him from going straight back to his crate once you have arrived home from work. If possible, encourage him to stay out and play with you for the evening. After a couple of hours, try taking him outside to go potty. You could also try introducing a command so that he eliminates on cue. To do this, you will just need to start repeating a word or phrase everytime you see him relieve himself, and eventually this phrase will become a command. I use "Be Quick" with my dogs.
it sound as though you are making good progress with your dog, which is great to hear. Keep up the excellent work!
