In Maine, we can shoot from unpaved roads, but can't have a loaded hunting firearm in the vehicle or touch a vehicle while the gun is loaded. The only exception is for "defense handguns" when the person has a concealed weapons permit.
Commonly, in the North Maine Woods, people stop to shoot grouse from the roads with a shotgun; also walk old roads, with or without dogs. Shooting down a gravel road with a rifle is frowned on for safety reasons, but not illegal.
As one warden explained it, a TC in .410/.45 or .35 Rem isn't regarded as a defense handgun and must be unloaded in a vehicle, but a 1911, .45ACP is generally considered a defense gun (unless the warden sees you shooting at game from the vehicle with it). I wouldn't want to run into a young warden who might interpret the law differently.