Access to images in otherwise restricted folders?

I'm not sure if this is one for AcidFree or Nodeaccess, as I use and like both. The problem is this: I have certain acidfree folders that are intended for a limited audience: members-only albums, if you will. Acidfree doesn't provide access restrictions, so I use Nodeaccess for per-node control by user role. Here's what happens:

I use Mass Import; it creates an album at, say, node 1242. I can restrict that node with nodeaccess, but the images are loaded into easily-guessed nodes 1243, 1244 and so on - which can still be directly viewed by editing the URL. Nodeaccess-ing each of 50 imported images is a pain. Is there some way that Acidfree could apply designated access controls during Mass Import?

And yes, I have had people try to scrape my site by querying successive node numbers.