One of the results of all this DR-DOS memory stick work was that I also created a bootable floppy disk image. I created it using Microsoft Virtual PC ... but the resulting disk image would be bootable in VirtualBox too. I manually edited the xml files to attach the virtual floppy disk in Virtual PC, as described here. This disk image just boots DR-DOS with a CD ROM driver, some memory management and a RAM Disk driver.
My next step will be to use this floppy disk image to build a bootable CD. I will then use that as the basis for my revised PDP-11 Live CD. I'll probably use SIMH for DOS since I don't expect that I'll be allowed to redistrubute the demo version of Ersatz-11 (although I think that Ersatz is a better emulator).