What do you use as the "length of your travel trailer"?

I would give the actual model number and the length of living space. I've owned a lot of RV's but it's been awhile and I don't see the reasoning behind adding hitch length to the overall length. If someone wants to store one in a garage or shed and needs to know OAL, then that should be provided but not advertised as a 21' trailer when the living space is only 18'.