One width high of chickenwire? In Europe that translate as about 90 cm (3 feet). I hope you have a roof on your enclosure, because adult rabbits can sure jump that high (and so can foxes)!
I'm hesitating giving you advise about the climbers:
You're looking for something that the rabbits would leave alone but that would not poison them? Or are you looking to provide them with extra munchies, planting on the outside and letting them nibble off the excess? I think they might quickly kill off most vegetation.
Is your
fence pretty sturdy? Can it take some weight?