I'd buy a step in harness. I have one from petsmart. We tried the ones that go over there heads but we couldn't get it past his mouth. It tags a tag team effort to get him into the step in one. Here's the one I have from pet smart. I think it itches him so i'm looking for one in a better fabric but this will do til he stops growing.
http://www.petsmart.com/global/produ...=1123535847551