According to our original design plans, which were standard in 2001, our gaucho is 45" wide (from the inside insulated wall) x 74" long, but I think the actual length is 72". (I'm 6'2", and my toes hang over just a bit.) Pretty sure the 45" is right, though. It's snug, but it works for us, even if you don't fit like spoons all night long.
Hike or die (or maybe just keep driving that Sportsmobile into the sunset).