Put in a large pond and pile the dirt behind it as your berm to shoot into.Opens up all sorts of landscaping ideas.
80 yards will give you a good amount of open space for a vehicle use. Maybe get a cheap SUV or van and use that for a blind from the roadside to shoot toward your house. Your targets could be set in a small tool shack for limited view from the neighbors. Afterwards, just drive it back to your garage. As long as the vehicle does not leave the property, maybe no need to license it. Neighbors will still hear your shots, but if they know the direction you are shooting, everything should be fine. If you must shoot from the house (rain, snow), do the opposite, put the target in the vehicle with the side door open to you.
LOL covered wagon ?