Check out coyoteroller.com
They make fence toppers that are rollers to prevent dogs from gaining any grip on the tops of fences.
It's a reasonable $28 for 14 ft. sections, doesn't mar the fence, won't look like a prison, and easy to install. Then when you move, you can remove them and take them with you. I'm sure an explanation to your landlord and you would get approval.
It's a great product! They just recently got a gov contract for installing them at an animal reservation to keep the wolves and coyote's out of the reserve. I've heard these work wonders and dogs stop attempting to even jump or climb fences. PLUS, it keeps other animals from jumping into your fenced area!