Best way to separate pinch welds

The replacement, cut off bedsides are ~30 miles out, it'll be a minute before I'm ready to retrieve them/ but they are complete cutoffs from an 8', 80s D150. They cut thru the front wall and all the way down the length of the bed, "just" inboard of the wheel wells. Other then drilling from the "inside" of the bed towards the outer wall, I know no other way to seperate the upper lip (where the stake pockets are) from the inner fenderwells and be able to use them, than to drill out every spot weld.....
Mine probably aren't "bad enough" to replace complete bedsides/ could get away with patch panels over the wheel wells.... but the PO was one who would scrape the sides of an airplane hanger pulling in/backing out..... and I have what I have here, which are the replacement full bedsides rustfree from Georgia already.... and Ive done the "patch panel" thing before and been disappointed. looked GREAT for ~2 years then it started rusting exactly at my seam.... so if I do complete bedsides, I won't have to worry about that.
Sounds like you all ready have the right idea of how to do it, I would definitely drill out the spot welds like you are saying, its probably less work than doing a patch and your gonna have a much better end result that will last, in this case if you have the whole panel might as well use the whole thing and make it count, and if your careful you can just drill through the bedside layer and leave the inner structure more or less unharmed, (that is if I'm imagining this right in my head) do the same to separate your replacements and then you'll have holes for plug welds, the spot weld cutters work ok but for me the hole they leave is a little on the big side so i just end up using a sharp drill bit and a light touch and an old putty knife, with practice you'll hardly leave a mark on the bottom flange