And a whole lot more demos requires lower. So there should be no problem filling a CD with working OSC, ECS and early AGA demos.
If there is no CD out there, maybe someone could make one? 
You could author a bootable CD on Amiga OS or on Windows with Nero.
The easiest way would be to put Workench on the CD to use to launch the demos from. Strip down WB as much as possible to save on memory. The only drawback with this solution is that you wouldn't be able to legally distribute it.
The other way would be to code your own front end to launch the demos from but if you don't have the skills it could be difficult to convince someone else to do it.
If it's something that you just want to do for yourself then go the WB route. I recommend starting out with a CDRW and just a few demos to start with in case you don't get it right first time. Quicker to burn and you shouldn't end up with any coasters.
You could always do a blog showing others how to do the Workbench CD and even upload an ISO sans WB somewhere.
By the way, I forgot to mention that the cover CDs from CU Amiga were bootable on CD32 and most discs have a selection of demos, some of which should run on an unexpanded CD32.
