Halfway through replacement process right now. Shock is on the UPS truck out for delivery and I was working from home today so I thought I'd remove everything and when the new shock arrives, just pop it in. Like everything else on this car, it's taken much longer than planned. The shock body wasn't stuck and did move, but it's very tight so I had to leave it bolted to the hub to keep it from spinning and use the spanner wrenches to turn the body. Then when it got closer to the end, I pulled the assembly and just braced it on the ground while turning (I don't have a bench or vise). There's just such a long threaded part inside the lower mount which is good since it's under so much load, but all those threads cause a lot of friction.
After getting the lower mount off, I realized that my lockrings were stuck. I haven't adjusted the preload in forever, just height so I guess they were frozen. The smaller lockring was basically rounding off from the spanner wrench so I had to put a pipe wrench on it and hammer on the spanner for the upper lockring. It finally came off, but it took 40 minutes for just this part. Add that to the 90 minutes it took to get the lower mount off plus the time to actually remove the strut and I'm 2.5 hours into a job I thought would take under an hour. Hopefully reassembly will go smoothly.
PSA for those who have coilovers. I'd recommend loosening the lockrings once in a while or they'll freeze. My lower one is basically destroyed. I can still use it, but with most of the turning points rounded off, if it ever gets stuck again, I'm going to have to cut it off. And the rear ones are sized differently than the front. They use the same wrench, but the diameter is about 1mm smaller. I thought I could replace my damaged one with a rear one I have laying around and discovered it won't fit.