http://4jndbnscrvmljnl3vynggebzvi5saz5gllk3iksdskgkmoq5oaqtxrqd.onion/meta/catalog.html
If you are unsure about adding more boards at the moment, my advice is to just do it anyway at least as a temporary measure. If adding them fails to attract people before 4chan comes back online, the boards can be closed and their threads moved to /gen/.