To snapshot the Ram Disk copy the def icon for it into ram as Disk.info. Snapshot it then copy it back to envarc:sys as def_ram.info. I'm not sure if you can do the same for the other def icons.
(I'm about to check that on my a1200, so expect an edit shortly ;-) )
--edit--
It's now changed to be right ;-)
The full path of envarc:sys is:
OS3.9:Prefs/Env-Archive/Sys
Replace OS3.9 with your WorkBench drive. If you copy it into env:sys instead, then it will disappear when you reboot.
