I use a type of no pull harness also. It's a collar with two straps that attach to the collar and through the legs. I switched to that because Kai could slip out of a regular collar easiliy.

I heard hemp is really durable and gets stronger as it ages...? Harnesses seem to be quite good also.

Do you have a fenced yard? I'd never leave Kai in our (fenced) yard alone because I'm paranoid that something will happen to him...(we live right behind a really "popular" alley) and because if he really wanted to get out, I'm sure he'd find a way. A fenced yard and maybe a large dog pen/run would be fairly safe I suppose. Although, you wouldn't have to worry about your dog getting out if it was inside with you.