probably you must setup a device every boot... you can't just "copy" or "restore" it to dev every time, as you know.
if you make a script, like you said, you can add files (scripts, but not devs) to filetool.lst using "tools" in the tinycore menu. that way if you change part of tinycore, that one script you name will restore every boot automatically. there is a "but!" the "but" is the script you add to must be a script that starts running after the restore script... otherwise you have to remaster.