In case you didn't know: Unreal seems to import .tif files now.

I don’t know if this is common knowledge or not, but when I started learning the engine last year I tried importing .tif’s and it always spat them back at me. Coming from an autodesk background, I basically use them exclusively. But purely by accident I just dragged and drop some Maya tiffs into the content browser, and viola: .tifs for days. Tried them out and worked fine.

Just an FYI for your workflow.