Think platform then. Either build your self one about 12' off the ground or find an old swingset you can modify. You should be good shooting down at an angle. A friend of mine had only a postage stamp for a yard in an urban area. He did have two trees ndwas able to mount a platform between. He shot downward only out maybe ten yards at most. Beyond that was a six foot fence and the neighbors house. He did it for years without incident.

Good luck