Unsurprisingly, using iPhoto over the network is completely useless. When you have 12,000+ photos (most of which are over 3MB in size), it's shocking that I would have even considered for a moment that I could store that data on a network and still have the same experience as using it locally. Well, experiment over, you can't.
Don't get me wrong, iPhoto still works, it just takes about 2 minutes to start up and about 4 to quit. And scrolling in the library is a constant beach ball affair.
However, the good news is that I don't really browse around in my old photos anyway after a while. I keep them because I want to have them forever, but I don't really need to look at them constantly. So, effectively, I'm using AirDisk as network storage only and I have a clean local library again.
When I start iPhoto, it uses my empty local library. If I want to browse the network photos, I hold down option when launching iPhoto and choose the network library (thanks for the tip, Shawn). When I want to import new photos, upload to Flickr, etc, I use the local library.
My only concern with this approach is what happens when I want to take photos from the local library and move them to the network library. I can't think of a good way other than copying them there and deleting them locally.
Maybe someone else has figured out a better way to do all of this. I can't be the only person who has a laptop and craploads of photos.