The Shawl

So I'm knitting a shawl...it is pretty and soft and nice...the problem is, I don't know how wide to make it. There isn't a pattern, per se...it is K5, YO, K across; K5, YO, Purl across. You alternate the rows for a stockinette stitch with a 5st garter stitch edge. So there really isn't a stopping point, just whenever you feel it is done. Well I don't feel it is done yet, but my circular needles are too short! So my question is this: can I get a circular needle that is more than 29" long? If anyone has any ideas, feel free to share with me. I want this shawl to be nice and wide enough for me. Thanks for your input.