I have a 2010 4cyl 2wd manual I'm going the (mild) overland route with. As it sits, Ive swapped the 3.73 open rear for a yukon duragrip lsd and 4.10s, and have 30x9.5 mud tires. It will soon have a 5k lb winch (building the mount now), a "half" tube front bumper, skidplate, and flat bed.
A limited slip/locker is going to be a must. I would also strongly suggest ditching the all terrains for something much more aggressive.
I second Dirtman in saying you'll want 4.56 gears, after a couple short overland "dry runs" I'm wishing I went all the way to 4.56, even with the manual trans.
Weight is a big concern for us. While a little extra in the back of a 2wd will help (to an extent) it really doesn't take much to start noticing a decrease in felt power. Your already at a slight disadvantage in the power department with the automatic and 31s, so for you to end up with a rig that's enjoyable to drive.. Especially off road.. your going to want to be real conscious of how much weight you add on.
A 5 gallon bucket full of sand weighs 60 pounds. Fill up enough buckets to weigh as much as everything you want to add to the truck for overland duty and take it on a dry run, see how it is. Definitely install a transmission temp guage first.
...and welcome!