It may not start/run with everything wet under there afterwards.The best way is to dry the engine off afterwards with compressed air before starting it up if possible.
Cover the little breather hole on the power steering fluid dip stick to keep water out.
Take along a spray can of WD40 to spray the distributor cap & wires. Moisture will collect inside the cap when you spray a hot engine and then let things cool off. The steam condenses inside the cooler plastic cap, and shorts the spark to ground.
The next day, the results of your Mr Clean efforts manifest themselves as moisture inside the distributor cap. Time for more WD 40 & a clean paper towel to wipe up the excess.
Try not to hit electronics directly with the higher pressure water, and cover the distributer and coil and you shouldn't have any problems. The compressed air is a good idea.