Cleaning the underside of your Taco

Any recommends on cleaning the underside of my new 07 Taco?

I live in Socal so it will probably never get more than a coating of road dust, oily road grime during the sporadic rain, and maybe the occasional jaunt on dirt roads going camping. I was thinking just a spray down with the spot-free rinse setting at the coin-op car wash. Would high pressure soap or the pre-soak have and pros/cons?

Also what about the engine bay? Maybe a light spray once every couple months with a simple wipe down when I wash the truck regularly?

 

dont know about the under side but if you spray you engine make sure its no hot and keep the moter running