Thanks for the headliner info. I have a wagon so getting the board out isn't a problem, but breaking it is more of one, as it is a lot heavier and more awkward. It's possible to get it out of a sedan through one of the door openings. It may be necessary, or at least helpful, to remove the front seats so you have more room to maneuver.

Was your windshield broken? If not, why the glass shards? I removed one from a parts car with little difficulty by using the following method:

Obtain a guitar string. One of the wound ones, not the plain kind. The smaller sizes work best, D or G, something in the .020-.030 range. Remove the moldings on the outside. Poke the guitar string through the adhesive, and with a sawing motion work your way around the edge of the glass. You will probably need a helper to get the bottom edge. Guide the string so it doesn't damage the edge of the dash pad or other interior moldings. After you have gone all the way around, go around again, as the adhesive will be trying to re-stick itself. Then tilt the glass forward at the top, slowly and carefully. Once again, a helper makes things a lot easier.