I've done it tons of times.....

Low Pressure Hose, High Pressure Pressure washer.

I rinse, degrease with APC of choice, hose off and just a mild dressing ontop.
No issues with needing to covering anything as long as you are moving the *wand-nozzle* and not flooding anything.

The ONLY thing I do try to stay clear of or keep minimal overspray is the back of the headlights area..