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!
Here is a free PBR texture by Alex Sychov for you to play with in Substance.
Senior Environment Artist with over 10 years of experience shared a metal plates wall texture (2048 x 2048 in .TGA format) on Cubebrush. The folder includes Substance Designer project.
Rendered in Marmoset.
Make sure to check out the artist’s artworks here.