You're talking about dogs that are high energy youngsters, and at 10 months they're still puppies. Kind of doggy pre-teens, so chewing is to be expected, but most of us channel and direct chewing to safe objects until our dogs grow out of it. Since these people aren't often home to supervise or train....
As to your basic problem - I think it's a lousy way to keep dogs, but neither your opinion nor mine matters. The only thing I think you can do is be honest with the owner. Tell her neither one of the dogs is settling until the very end of a 15-minute walk, which makes it difficult to walk them, and it would be better for both them and you if you could take them for half hour walks. Of course you need to decide up front: Are you willing to speak up when it could mean losing the business? If the owner doesn't fire you over it but refuses to pay for longer walks, will you go on as presently, or quit?
If you decide to speak up and only continue if you get the longer walks, don't do it hesitantly and let yourself be bulldozed into continuing. Maybe you're no expert, but you're right.
As to your basic problem - I think it's a lousy way to keep dogs, but neither your opinion nor mine matters. The only thing I think you can do is be honest with the owner. Tell her neither one of the dogs is settling until the very end of a 15-minute walk, which makes it difficult to walk them, and it would be better for both them and you if you could take them for half hour walks. Of course you need to decide up front: Are you willing to speak up when it could mean losing the business? If the owner doesn't fire you over it but refuses to pay for longer walks, will you go on as presently, or quit?
If you decide to speak up and only continue if you get the longer walks, don't do it hesitantly and let yourself be bulldozed into continuing. Maybe you're no expert, but you're right.