As long as they are getting enough exercise and attention when you're around I wouldn't hesitate in the least to crate him when you leave! Especially if he calms down and chills when you crate him, down time is just as important for puppies as stimulation IMO... How long are you leaving him in the crate at a time?
Tango, lab mix 10/01/2000
Scarlett, cattle dog mix 04/01/2007
Sasha, GSD 02/01/2008