Since it appears that the front is knit in one piece--I originally thought it must be knit in two pieces.
What I would do is write out the line for the back and the corresponding line for the front so you don't get confused as to which line your are on for each side. You can leave out the selvedge edge since you won't need them for seaming, and you'll have to reverse all the stitches that would have been on the wrong side. In this case it just looks like you'd knit them all rather than purl them all.
Since it's only two short sides to seam, rather than seaming sleeves and sewing them in and such, if it gets too confusing to work it in the round, there wouldn't be all that much seaming to do.