My understanding on the road right of way, here in Minnesota, is controlled by the township board, or is it is a county road, it is the county commissioners.  State highways would be controlled by the DOT of that state.

Down in Iowa, all roads, except state highways, are controlled by the county commissioners.  Having said that, I do not think the county commissioners are opposed to having the manure hose laying in the ditch of the right of way.  The reason for that is, particularly in the spring, when frost is coming out,  and the heavy tanks are hauling manure, they will cause alot of damage to the shoulders and approaches with continuous hauling.  A hose will not do damage to the roadway, unless there is a spill. 

I am sure if the county commissioners okay the hose in the right of way, they would also be insisting that the manure contractor  has sufficient liability insurance, in case of a spill.