Since the "tail" isn't really a tail (it's a pair of legs), it shouldn't really be included in the length. Then again, most measurments are based on visual estimates anyway, so they will be off by an inch or two anyway. It's not too easy to get a pede to cooperate and let itself be measured accurately!
See Wade, there you go confirming stuff for me without me asking. I was wondering recently if the caudal legs should be included in the measurments or just the trunk. I personally used just the trunk length myself.