Hi Elliott, This is a great breakdown and very generous in sharing your process and insights, you came a long way from the vending machine days!
Are you planning on releasing the UE4 project to the public? Or only builds? I'd love to play around with it in the editor if possible!
Take a look at a pack of more than 20 pieces by Juan Nahuel N. that you can reuse to do something you want. These were created for Fulgora Tank and his other hard surface projects.
The .zip includes each piece in .obj format (decimated) and one .ztl with all the pieces together (different subtools).
If you have some questions you can write Juan.