I see tripods everyday and they usually dont get a second look. The only ones that do are the ones that are very small and compact because of the heavy density that they have due to their size. Yours should be fine. However you might want to read the limits of liability on your ticket sleeve. The airlines wont pay for anything that is damaged especially in carry on.

As far as FWAAA says and the number of bags: I tried to get to the bottom of this issue over a year ago. I can tell you that it is murky. While the TSA website tells you what the number of bags are that are allowed, the TSA doesnt take enforcement action. As far as checkpoint screeners are concerned, they dont care. At DEN it is up to the private ticket checkers before the checkpoint to inform the pax that they are over the limit on the number or size of carry on.