Yeah, I took a quick look at your Google links too. Although circular, it's overkill for your project and pattern. The simplest way would be to duplicate your stitch, especially if you don't want to waste experimentation time.
And, like you and Amy mention, Intarsia couldn't happen on circ's anyway.
It was in the back of my mind to write (yet another long) message about that issue with your green yarn which you just mentioned. I created my own workaround on straights and know it's not something everyone would agree with....but (maybe) worth a try on circulars?
Part of the problem is the cutting, which you wouldn't have to necessarily do until you finished up the piece, you could carry the brown (leaving horizontal bars as you go, like with Fair Isle) and pick up/drop the green like Intarsia (creating diagonal bars as you go). Within the wrong side, you can hand-adjust the tension where the colors meet up...just make sure to do it THEN.
Later, to finish up, you could cut the loose bars roughly in the middle (you'll know best as you look at your configuration) and tie the ends off (not super tight & not loose)...regardless of color, since it's on the wrong side. You could avoid some weaving in this way....but I understand a lot of people frown on this approach because you run the risk of losing some elasticity and could create puckering. I've done it already (on straights) and it saved time weaving....even if it's not the most technically proper thing to do.
On a small piece like you're doing, I doubt it would be a real problem.....but I would wash it once to make sure it's going to look as intended before I'd send it off to the intended wearer.