welp, for what its worth, after all that research fluid film definitely sounded like the way to go. i think my second choice would have been amsoil HD metal protector, sounds like it is a bit more of a permanent coating, so might be favorable if youre expecting lots physical contact.
anyway, used about 2 cans on just wheel wells, then 3-4 on the rest of the underside. used an outdoor lift at my buddies work, wind was a bit fierce so got quite a bit of overspray on one side of my truck. seems like it will just wash off with soap and water though.
http://i113.photobucket.com/albums/n202/misplacedape/PhotoGrid_1411766647444_zpsfa04b1a2.jpg