"Can this stuff be delivered by crop duster?"
You would need a big nozzle, it can be a bit chunky. A truck with a pressurized hose outlet to the side might work. Vacumn pumps are used in the field.
Someone must have the right equiptment down there. You don't want to freak out the good guys however.
How about one of those C130s the forest fire fighters use?
mmmmm..........chunky.........
A tractor with a power take off (PTO) hooked to a "honey wagon" will do the job. You just put up the "spreader" plate that goes in front of the inlet/outlet, and set the pump to empty the wagon rather than fill it. Did that once a long time ago with my cousin when he was doing a neighbor's chores while the neighbor was on vacation. (mid summer when not much is happening on a farm, other than taking care of the animals). Grass and corn grew real well down in that corner of the field that year. :)
'Course it will get both sides of the road, unless you do it from inside the fence on the side of the road you wish to target.