No, I didn't find the best solution from the box.
But I noticed that you can do external plugin for FeedManager plugin and calculate this new value.
I added new features one year ago.
https://www.foxnetsoft.com/documentation-nopfeedmanager#q14If you can't do it I'll do it for you, but we'll have static values in the new DLL file.
What do you think about it?