I'm afraid not. I had not a lot of time to study possible solutions, but the main problem is still file duplication for spotlight note previews. I know some don't care about images in spolight, but feels very strange to us to ship something without image support.
I'm going to go out on a limb here and say that while 'some' people want to see images in the preview, the real important part is search in spotlight. As a version 1 of the spotlight plugin, I would be happy with simply seeing the note 'name' and a bear icon. This would be a HUGE WIN. Version 2 could include the image preview. People in the Apple world are used to incremental updates to their applications so I don't think you'd be ruffling any feathers by doing incremental releases on the search plugin. However, the longer it takes to get the spotlight feature out, the more likely people are to become unhappy with the core application. To put it simply, lack of a spotlight plugin may cause people to stop using the application, but lack of an image preview in spotlight results probably won't.
+1 to what Trever said - I use images myself and would love image preview when it's ready, but would much prefer to find the notes with no preview than to not find them at all. Let's start with what you've already got and go from there!