Yes, as Frederick explained, my width reference was explicitly to the lighting
requirement. 80" is a popular width because it is as wide as the manufacturer can go without incurring the cost of those extra lights
and wiring. Most trailers are wider, including many moulded fiberglass trailers, including mine. The lights
are not important - they're just a reason for the remarkable consistency in width. It would be very surprising to find a small trailer any wider than 80".
I also had a typo (now fixed) in my earlier post: the 80" or 6'8" width is 2.0 m. The 2.6 metre (102") value which I originally listed is the maximum width for a normal trailer - yes, that's considerably more than 8 feet. Eight feet (96") was the normal width of a large RV for years, but now "wide body" means the maximum width or very close (101" to 102").