That's a tough one, your truck is rare for the after market. I think you may have to look at doing something custom. 3" with some bigger tires should do it. 3" is a common size for body lifts, maybe you could buy a generic body lift and install it your self.
If you are unfamiliar with body lifts, generally you just unbolt the body, lift it up using a jack and install the body lift spacers before bolting the body back to the frame.