you contradicted yourself like 3 times lol do you want to lower it with bags or do you want the bags to help out leveling your truck when you have a load? if you inflate the bags you should go up around 2-3 inches depending on what bags you have, but when you deflate them you'll go back to your stock height.
if your wanting some help with a load (stereo weight) then just bag the rear end, it shouldnt be too hard, but if your wanting to slam your truck on the ground with some bags, then sell the truck to someone who could use the 4wd and buy a 2wd lol 4wd is pointless when your 1/4 inch off the ground. lol
(all of this is imo)
is this what your asking?