I've got some good news and some bad news.At this point, I see no other alternative than leashing him to go out even in my fenced yard and restricting his outside time until we can solve the problem of the yard. I have two other large dogs, so he's not the only pet with which I have to contend he's just the only high-maintenance one.
GOOD NEWS: There is a product you attach between all the posts of your fence. It is a rod with a metal tube around it. When your dog gets to the top of the fence, the tube rolls over the rod keeping the dog from getting traction to pull himself over the fence. I am picturing a chain link fence here. It would make it impossible for the dog to climb over the fence because he just can't get enough traction to pull himself over it.
BAD NEWS: I don't remember the name of the product or where I saw it. I THINK it was on another board. There was a thread about an escape artist dog and this product was brought up along with a link to a web site. Sorry, thats all I can help you with now. I'm sure this would solve your problem.