Use My Own Photo or Artwork for Full Screen Start Menu?

Hi,

I've tried asking this on the Windows reddit & Microsoft community many times but I never get an answer. I like making my PC look like Windows 7 and 8.1 and Stardock's software does a great job at this. I have a Windows 8 WindowBlinds10 theme and a start button for Start10. Windows 10 has an option for a full screen start menu in the Settings. I like this as it completes the look of 8.1 however the background for it is the same as my desktop. I created artwork with "Start" at the top similar to the default 8.1 artwork. I want to use this instead of my desktop wallpaper. I cannot seem to figure out how to do this. Does anyone know how I can do so?

My Start Screen

Original 8.1 Start Screen