Yup, it's pretty fun to play around with.
I think a couple of years ago somebody made a level they called "Bespin SE" which was just the secret level with a few modifications, such as adding Darth Vader (although if I recall, the guy implemented the textures wrong, so you still had to modify it in order to see Vader instead of Kyle/Mara). He also made it so that Boba Fett has a ton more hit points, and his blaster cannot be pulled (why, I don't know, except to make him tougher).
I wouldn't know where to find it, but maybe someone will post it.
Another thing to note is that you can kill the saber users easily with your blaster (ie: they are unable to block shots, unlike the saber users in most SP levels).
I actually used to have a hilarious screenshot of Kyle standing over a (dead) Luke on top of the Falcon. ; )