Your best bet is to learn how to do everthing yourself. Getting sponsered is not easy, and even if you did, you would ultimately be working for your sponsor, going where they want when they want you too. And you can bet on having their company logo plastered all over the vehicle.
Get a job and start saving money, that's the best way to hook up your truck. Build it for yourself, no one else matters. Most parts are usually in the same ballpark price, so that's kind of futile searching for parts. Try a few different mail order or local places, try to get all of your stuff from the same people, it will help dramamtically in the long run.