I agree about knitting it flat, one piece. I don't see anything to complicate knitting it all as one piece much. I'd perhaps add a "side seam" by slipping a stitch on the knit side where the side seam would be if there were one. I tried this recently and liked the result. I'd start by working the ribbing in the color I chose and then add the 2nd color for the main body at the appropriate spot. You'll need two balls of the color for the fronts, one for each side, but that's definitely doable. A three-needle bind off for the shoulders and those two seams are gone also. Looks like an interesting and fun knit.
Denial, anger, bargaining, depression, acceptance...the five stages of frogging.