Alright, after days of grinding my teeth to this issue I finally have resolved it. The first issue was: using a dated version of Mod Organizer, I was using 1.2.11. I'm used to most mods being ordered from top to bottom, newest to oldest on Nexus Mods, and the author has elected to order MO the opposite way. Anyway, that's my fault for assuming, shame on me. But, updating wasn't quite enough. MO still wasn't presenting the .dll to the virtual directory properly, some folks speculate that it's an issue with a hardcoded file path inside of the Uncapper itself. Anyway, when I tried manually moving the Uncapper .dll out of the MO/Mods directory, into skyrim/data/SKSE/Plugins, while leaving the Uncapper .ini inside the MO/Mods directory, using v1.2.11, it had no effect, however, after updating to MO v1.2.14, and manually moving the .dll, it worked! I have tested and verified that this is working by setting destruction under buseskillexpgainmults* to 5000.0, then, taking poor shadowmere out in the woods for some testing. One tick of "flames", and I start leveling, and continue leveling until I get bored of watching it. I then set it back to 0.0, which is what SXP needs to work properly, and I can empty my mana bar on Shadowmere over and over with no effect, so I feel pretty confident that it is now working properly!
