The sound deadener stuff really makes a difference... I'd recommend doing your doors. (But dont do what I did and do the very top strip, or go as close to the panel clips...leave another inch surround. I didnt figure that out til I tried to mount the door panel)
I used kil mat on my doors. Similar to fat mat...one of the cheap alternatives to the real stuff and I'm quite impressed.
As seen I pretty much did full coverage on the outer skin and on the inner skin. Then did 1/2 coverage on the outside of the inner skin.
I went from no door panels/no sound deadening/no carpet/no weatherstrip/open trans tunnel with extra cut out for duals....basically 2 seats and a dash board in.... truck was like the inside of a 50 gallon drum at highway speeds. Couldnt hold a conversation.
Added weatherstrip. Weathersrip alone probably quieted it down by 100%.
Put in a 85% sealed off trans tunnel. Probably quieted it down another 100%
Added all the kilmat to the doors, quieted it down another 100%.
Took plastic sheet and tuck taped all the ports shut in the doors.(didnt want to fool around with that 3m ribbon sealer stuff) and the truck got another 25% quieter.
Can fly down the highway and have a conversation now. Amazing how much the "little" things do to ride quality and pleasure of driving it.
Still plan on making door panels with closed cell foam layering, kilmatting the trans tunnel and entire rear section/wall of the cab. Every little thing really makes the truck that much more pleasurable to drive and makes it not just a "bush buggy".