Stitch mp3s with same image in watched folder

Hi community,

I have bunch of mp3 podcast that I need to convert to mp4. Every podcas needs to show the same image.
Because of the ease I was trying to use a watched folder for this. Problem is I can't find a way to use stitched clips in a watch folder. The image I got fixed setup in a preset and this works like expected.   

Anybody has an idea please? Or should this be handled like a feature request?

Thanks,

Geert