Finally got the chance to work on my truck today. My bro-in-law came up and we tried what you said, except we used dawn dish liquid instead of wd40 (for ease of clean up), and it worked GREAT! Popped right out.
Got the patched up front fenders and my homemade front bumper on, it's starting to look like my old Dodge again!
After getting the windshield out I could see that the rust didn't extend down into the lip that the ws gasket fits onto, so the repair won't be as hard as I thought it might be.