I propose trying to teach them to get along w/ each other.  They can co-exist despite the different communication systems.  I do have a few cats that have attempted the stalk on my rabbits, but both rabbits seem to be faster than the cats (really I was surprised).  Also bunnies are able to defend themselves and let a cat know they have no interest in their shananagins (sp?).  You could try clipping a sheet over the pen, which will likely deter the kitten, but my feeling is that if she keeps kitten’s claws trimmed, they can co-exist and maybe become friends.

A friend of mine has 2 dogs, 2 cats, 2 rabbits and two kids (maybe her house is an ark…). Personally, cats with rabbits scare me to death. When she got her first cat, it stalked the bunnies. I told her to keep an eye out (the bunnies had a bun condo with an open run area– easy for the cat to jump into). When I visited a few months later, the cat had jumped into the open area and was just sitting there, hanging out with his friends, the rabbits. Weird. Anyway, she taught them to be friends, so I guess it can be done! Maybe it was easier because it started as a kitten. We had a fully grown cat stay with us for a little bit, and it didn’t go as well.

I have always had cats and rabbits in the same house together. I make the litterbox situation work by putting the cat boxes in areas where the buns can’t/don’t go into to and I make sure that the cats know that the buns cage/pen/whatever you’re using is BUN ONLY. They are not allowed in there for any reason. The rabbits and buns can hang out together in neutral territory.

How about a couple of meters of cat netting, the kind they use to create safe cat habitats in yards. Glue some press studs round the door frame and fix it on that way when you are not home.