you can get water in the engine bay, the key is to ostay away from important electrical stuff, i usually cover up anything important. sometimes ECUs are in the bay, big fuse boxes, any inline 4 or 6cyle i try to keep water away from plugs boots water can seep down into the plug holes. so basically just try to bag up, and zip tie things that could possible cause problems.
but i usually use a few different cleaners. but i like a 80/20 mix off purple power and water, let sit for a few hose till its foamy, go to work with a brush on soiled areas, and then pressure wash off.