When we did our driver side (first one we ever did) it helped to cut the quarter just below where the quarter meets the roof panel seam. With finesse, we were able to break the last hidden spot welds holding the seam together by using a flat prybar from below. You do have to be very careful so you don't ruin the roof curve.
We also cut vertically just behind the door jamb and would probe behind the quarter's jamb to find those last hidden spotwelds.
Overall, we did cut whenever it seemed like it would help to access spotwelds.
Good Luck, and take your time. It can be done, check my sig pic link.
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