You sure can!
A couple of things–if you are going to knit them in the round- do a new gauge swatch because your gauge will almost always vary a bit when you knit in the round. Fortunately, there’s a trick to doing an “in the round” gauge swatch flat. What you do is:
On your circular needle or with two of your double points, do this:
[li]Cast on enough stitches for about a four inch wide swatch.[/li][li]Knit your first row.[/li][li]Here’s the key step: Slide the stitches to the opposite end of the needle, [B]without[/B] turning the work.[/li][li] Knit the next row if you are doing stockinette or purl if you are doing garter stitch (this may seem counter-intuitive, but when you are knitting in the round, knitting every round produces stockinette and knitting one round, purling one round produces garter stitch–so yes you can do garter stitch in the round).[/li][li]Keep doing the above steps until your swatch is long enough to measure.[/li][li] Bind off the swatch and measure your gauge! Or you can slide the stitches to a stitch holder to make it easier to rip them out if you want to.[/li][/ul]
Note that you will have long floats at the back of your work from sliding it over.
Have fun with “modding” your pattern! It is definitely nice to NOT have to seam.