Awesome variety of replies and advice. I found the idea of the "long measuring tape and Google Maps satellite view for my smart phone app especially helpful.
We routinely do: research site specs online, talk with specific campground, walk or drive the grounds, hang back of TT over the edge, park TV alongside or elsewhere nearby.
The end answer does appear to be, "there is no real industry standard; just various interpretations of the definition and/or meaning of size". Indicating once and for all that indeed - size matters!
Thanks all!