I would agree that there is no real way to say which is cheaper, too many variables.
I just like the extra options with my TT. Our first outing was to a three day music festival on big ranch in the middle of nowhere. Camping only or drive at least 30-60 miles to the nearest motel.
I will also use mine for work if I have a job out of town. If it's more than one night, it is cheaper to use a state campground instead of a motel. Since I don't usually like the Motel 6 etc. And so far campgrounds have been quieter than a motel.