What name brand, model, and year bike do you have?

I'm no major fan of any kinda cable lock, but the vinyl covered thick ones do have some credibility...

Your idea may be good for when you're inside of class. However, overnight, I wouldn't chance anything. Your bike should accompany you to bed at night.... I wouldn't leave my lock out for extended periods of time either, so that would-be-thieves can study it.

Get either the OnGuard U-Lock or the New York Fahgettaboudit U-Lock. If you must lock-up outside overnight, everything should come with you except for the rear wheel, handlebars, frame, and fork.
Get an old used crappy-looking leather seat, that has some wear issues. Wrap the bike tubes up with painted duct tape.