As was inevitable, I've built a thing that is too complex, uses too much bandwidth, and is too artsy to be a screensaver so I've decided it's an installation. The Pi is a web server, holds all the files and does Imagemagick processing. So anything I can do to make it slicker while demonstrating it seems worth the effort. I think I will try @belltown 's way first, but what you describe sounds like second choice for sure, If I get there I'll ask again about how I might go about that.
Thanks both of you for answering, I appreciate it.