You're going to knit every row; that's what all that sliding business is going to allow.
Were you turning the work, you would have to alternate knit and purl rows... but since you are working with the *same side of the fabric* facing you always, you will knit every row - just like you would in the round.
Go ahead and knit your swatch on your dpns. There's nothing to stop you from doing that at all. They are, after all, regular needles without a bobble on the end. They'll work fine whether you work flat, alternating knit and purl, or simulate in the round, by squishing across to the other side and knitting every row.