Not exactly what you're asking, but I live in an apt with the same restrictions (although not that high up).

YardBirds (western US) has some nice looking hooks/holders for pots of different sizes. They aren't real cheap, but they look nice and hang pots over the outside railing.

While I'm saving money for more of these , I've bought some L shaped *rafter hooks* or hooks for holding tools in the garage or workshop. You might find a way to use them.

The url included here show a picture of a rafter hook.

Here is a link that might be useful: Rafter hook