Well, after blowing away SKSE and my attempted installs of SkyUI5, I went with NMM, still got the issue of SkyUI5 saying that SKSE wasn't installed (despite the fact that it was installed through Steam in the first place), various attempts to install SKSE the way it's aparently supposed to be done yet SkyUI still couldn't detect its installation, then after feeding SKSE as a downloaded file to NMM (latest version I believe, 7z format), I got that to install, then SkyUI5 finally installed, then the game immediately crashed and only started working again once SkyUI5 was deactivated, then I installed 5.1 because 5.2 is marked as an open alpha (yet for some reason nexusmods comes straight up with that version as if it's the stable version), (I removed 5.2 before installing 5.1) but then 5.1 is also marked as alpha status, the game started, but still no new UI.
A smidgen frustrated.