Averaging B&W image

So I'm trying to find something similar to the Blur->average in photoshop. From what I can tell, it's not available. Essentially I'm trying to find a way to figure out roughly how much of the print surface will be inked. Our presses are flexographic, so every color that is printed is converted to a black & white image where the black becomes the raised relief part of the plate that prints. 

At any rate, I'm trying to find a way to have a script calculate the total ink coverage so that when pantone colors are being mixed, the printers have a better idea of how much ink to make. If I convert ink to black and the print area to white and drag it into PS, with blur -> average I get a percentage value for the black (35% for example) which tells me the print is 35% covered with ink. 

Is there a way to do this in Illustrator? Doing this Photoshop method for every job is not something I want to attempt. I've seen the possible solution with InkQuest mentioned in searching here but was hoping maybe there was a way to do this with Generative recolor (I've attempted without success). All I really want to get to is that percentage, and it doesn't really have to be that precise. Increments of 5 or even 10% would be much better than what we have now, which is printers eyeballing it and taking a guess.