You would need a permit, 8.5 ft wide is max without a permit. I don’t believe you would need an escort vehicle. Check with MN Dot.
Looks like you will need mirrors that allow you to see at least 200 feet behind and red 18 x 18″ flags on the corners at the widest points.
Obtaining Oversize/Overweight Permits.
The road authority over whose roadway you wish to travel must issue the Oversize/ Overweight
Transportation Permit. For Interstate or State Trunk Highways, the road authority is Mn/DOT. For local
roads, the road authority can be the county, city, township or municipality. Mn/DOT does not issue
permits for travel over local roads
Application forms for a permit for use of state highways (Interstates, U.S. Highways, and MN Trunk
Highways), and additional information regarding oversize and overweight load restrictions can be
obtained at: http://www.dot.state.mn.us/cvo/oversize/oversize.html
Rear Visibility Required. Vehicle shall be equipped with a rear view mirror(s) that provides the driver with a view of the highway for a distance of at least 200 feet to the rear of the vehicle.
Flags. Red or orange warning flags are to be displayed when load is more than 3 feet ahead of the front bumper or 4 feet or more beyond the rear of the vehicle; when a vehicle or load exceeds 9 feet in width; or when a vehicle/load exceeds legal vehicle length. Flags must be 18 inches square and in good repair. Flags must be secured at the extreme tips of front and rear overhang, at the widest points and each corner of over width loads and fully visible to traffic.