Image Shader with Proxy File Path for Viewport

This is pretty simple. My request is to add a second file path to the image shader for viewport proxies. I work with massive 16K image sequences. For the render, I use full-resolution JPEGs, but in the viewport, I use an image size that is only 10% of the original. I have to go back and forth between full and proxy size when programming camera work and scene renders.

Another option would be to modify the material output shader to have a separate viewport output or create two separate output shaders. One for renders/both, one for the viewport. If no viewport output shader is present, then the render output defaults to both render and viewport.