Interseeding cowpeas into sunflower at the same time

Hi,
I have about 12 acres of land and for the next year I am thinking to do a tillage and then plant sunflower and cowpeas in between, at the same time. Sunflower grows big, while cowpeas stay smaller. The goal is to harvest sunflower seeds, cowpeas is just for weed control. I have seen Gabe Brown doing this with corn (videos bellow). According to Gabe, this works, but there will be a lower production in corn (how much less?).
Have any of you tried this so far? How did it work in your case? Or maybe you know somebody who tried this something similar.

Links:
 or maybe https://www.youtube.com/watch?v=QwoGCDdCzeU, forgot the video exact time

I don’t have an acreage, but I do grow both sunflowers and cowpeas in my garden. My first thought is that in my climate (Chicago, 5b), they have different sowing times.  I sow sunflowers early in spring (even overwinter works). Sunflowers sprout fairly early. Cowpeas, on the other hand, won’t sprout until the ground is much warmer, in June or around the time that tomatoes and peppers are planted out.

Maybe you have a different climate, though, or maybe it’s ok for your purposes for the cowpeas to sit in cold soil while the sunflowers are growing.

I don't know if it is just me, but I struggle growing anything close to sunflowers. I believe they have allelopathic qualities? I'm not saying its impossible but something that might work against you.