[H3less]

With your stereo off, air off, and windows open you slowly and very gingerly ease your way up to the object you do not want to scrape, crunch or have any other nastiness happen to your truck, then move to the point you can hear the noise you think it would make when you come in contact with those bad things and you will know you are there! Then you make a permanent record of that point and mentally back it off a couple of inches and you will know when to stop in the future.