^^^
You’re close Doug, but with just a few sewing skills it can be accomplished as asked.
Look closely at the slider body to get the designation – 5N – on this one,

3C on another –

It can be anywhere. A magnifier helps. Call Patagonia Customer Service tell them your story and ask for two sliders. (They sent me 5 complete zippers to install in my “Tropical Comfort” Hoodys.)
Pick apart the sewing holding the top of the zipper, being careful not to separate the coils. If you do, use the bottom slider to rejoin them. Stuff the joined coil into the “tail” of the new slider until it hits the separating divider. (The top side of a slider has more height to accommodate the coil, and a guide rail.) Insert a Very thin sharp probe into “nose” of the slider and separate one side of the coil from the other, all the while applying pressure from the bottom to induce the coil to split. Creative language helps.
Resew the zipper into place.
In the first photo I created the two tabs to help with the tensioning, I then tried it without tails and it worked just as well. The key to success is a “probe” that will get the job done. (I used the probe on the other end of a fly tying dubbing brush.)
I’d be happy to send you this zipper to practice with. PM or greg attt smgm dottt org