Sorry, but how long did he take to chew through a long-line? The one we have is pretty solid and would take some chewing (not impossible, but it's not going to be a 5 min job...)
I know others have used horse lunge lines as long-lines, which I imagine would stand up to more chewing....

Otherwise I would revert to what has been suggested - not letting him out unsupervised.... you could always use baby gates so that a door could be left open for fresh air in this hot weather...
How would you propose using an anti-bark collar??
How would you know what he was barking at...? What would you do when he discovered that barking was in and of itself more rewarding than the air-release noise was upsetting...?
Someone on another forum was recently asking for advice on puppy biting, and reported back that things were progressing well, apart from the previous night when the pup was going absolutely ballistic and nothing would calm it down... they put it down to his OTT puppy behaviour, but it turned out someone had broken into their back garden and stolen their bikes.... unless you can see what he is barking at, how will you know it's appropriate to punish him for it?
And do you really think that using an aversive collar to interrupt is going to encourage him to want to come to you?
Another option is to find something irresistable so you can call him in from barking with that.... (when Honey decided to start barking at horses and cows on our walks, we used a squeaky toy to divert her attention back on to us...) - the danger with this is that they learn the barking achieves a reward, so it needs to be done alongside other training...
I really do understand how frustrating a barking dog is - especially one who has learned that his barking is a great way to get a game of chase from its owner.... but I passionately believe that aversive training has no place in modern dog training (there may be some occassions where life was at stake where I can understand why people go down that route, but I still don't agree with it...)
Obviously, just my opinion...
