If you want a 3-4 inch lift you need to replace the shocks (150-300) and new springs (140-180) and again crank the T-bars ... Link: http://www.outdoorwire.com/4x4/isuzu/tech/amigolift/?
As for off roading in the sand ... did you air down? Running at 15-18 Lbs will make the world of difference.
As for the rear tire you could relocate it to the roof via a roof rack. Or on the days that you run the sand drop the spare and carry it in the truck.