Im no expert but does he do well with "stay" inside? If so you can work with him slowly. Start with him staying in the house...then at the front door...then at the front door with the door open. Only move to the next spot when he has successfully mastered th spot before (also make him stay until he is calm, this will help keep him from bolting due to excitement). Once you get to the edge of the grass (or wherever you decide is his boundary) make stay harder and harder. Have him stay and then praise him. Have him stay as you walk away and the come back. Roll a ball or a bone but do not allow him to get it. The more you do it the better!
Hope this is some help!
