Wouldn't it be easier to pull the hard drive completely, then use the Ubuntu Customisation Kit to create an ISO image with everything stripped out that you don't want/need ?
The problems are probably going to be -
a) getting the examining board to define "minimal" .. a list of what they DON'T want would help.
b) getting them to verify that the end product suits their needs.
Another option would be to swap out the hard drive for a blank one .. but again, they/you haven't said what they'll accept as an installed OS, they really need to define what they want.
Wouldn't they just be happy with hard drive removal, then running a standard distro from a LiveCD (so it's non-modifiable), then saving data to a BLANK USB stick ? .. you can then just refit the hard drive after the exams.