A hose won't do it. I'd use a bucket of clean (no soap) water after the hose. A simple cloth wipe, rinse in bucket but ring the dirty water outside the bucket. I've washed many nice cars with nothing but clean water, clean clothes, and a towel wipedown. Its the thin film of dirt left after the hose that offends you. I agree, dried mud equals rust, but not in New Mexico because we rarely have mud. . . . but when we do I wash and wipe it off. Stay on it.