Bob, where did you find your info? I don't know of anyplace that limits it to 8'. There is a requirement for different lights on an 8-6 trailer but that's the only restriction I know. My trailer for the TC is over 8' and I don't think I'm restricted anywhere.
On edit, found this on a website:
"There are 15 states that allow only 8'0" trailer width, but federal rules dictate that 102". or 8'6" is the national size limit, so interstate highways in all states are 8'6". This means that some roads in some states have 8' limits. You can buy the "Motor Carrier's Road Atlas" at any truck stop to see a map of roads in all states that have width restricted to 8".
When I looked, only found 1 state AZ I think and DC that had an 8' limit. I wouldn't worry about an 8.5 ft trailer at all.
Charlie