I used one plant to cover my 20x10 nursery for shade. In 18 months the roof is ready to collapse from the weight (I would estimate it at 200+lbs, maybe more). I did not plan for it to weigh so much.
How tight is the fence? How much wind do you get? Wind gusts are going to cause the fence to act like a sail. If I remember right you are at the top of a hill. If its built solid it should not be a problem.
Passiflora grows very quickly, and will easily support 20+ feet in either direction. The weight has an issue, and if trees are close to the fence it will crawl over the neighboring trees slowing suffocating them.
Constant maintenance and trimming too. Loves water, lots of water.