Oh yeah I also forgot to mention Simple UI is compatible with Wookie's 12 slot toolbelt and Khaine's 15 slot toolbelt. No need to install any thing extra. You will not have toolbelt keys displayed though. That info has been added to OP as well.
Just sharing pics of how Simple UI 7.1 option looks on 3440x1440 2.39:1, and 5120x1440 32:9. I keep wanting to stay with 32:9 but I think there is still a little too much stretch/fisheye and I'm susceptible to motion sickness and sometimes its too much. Left HUD is still way out there and I haven't determined what is causing my outer edges to dim only in 5120x1440, but the corners are very dark and the left/right info is hard to see. Happens fullscreen and windowed. I will be sticking with Simple UI 7.1 on 3440x1440. It is not as tall as Wookie's whose interferes with the bottom row of my crafting que. I am using AGF's 72 backpack with no interference. Other mods noticeable in the pictures if anyone wonders are Vehicle Madness, Darker and Vibrance Reshade preset 2, Better Biomes, World Lighting Tuned, GNS Weather, Brighter Wasteland, and Wraithe's Craftable Backpacks 72 version. Print screen messes with my HDR so images are overbright with some overspill.
***EDIT: I figured out why my screen edges were dimming on 32:9. The Reshade preset (Darker and Vibrance Ambience Reshade https://www.nexusmods.com/7daystodie/mods/6903) I was using had vignette.fx radius set to 2. Adjusting it out to three pushed the dimming all the way off the edges.