Just want to re-iterate the keep it simple theme. Examples: I have taken a bone-stock YJ on 30" tires through some of the "hardest" Moab trails (hell's revenge, fins 'n' things, 7 mile rim, lockhart basin) and the only issue was occasionally dragging the trailer hitch. My LJ rubicon went up to wheeler lake in Colorado when it was stock and I had no need for the lockers (also on "only" 31 inch tires) I too travel alone a lot (I know many think this is nuts) and the most important "upgrades" may be more to your mindset and your camping gear than your jeep. A way to air up; a winch, tree strap & snatch block; I high lift (to swap on the spare or move the jeep sideways); a lithium-ion booster pack; a good radio (pick your flavor CB or HAM); and maybe a SPOT locator if you are really going to BFE. Always tell people what your plan is and where you think you'll be over the course of your trip. This might be the most important thing you do. You may want to consider spare fuel (but honestly not a priority) but definitely a way to carry a good bit of water (I think 2-3 gallons as a minimum) and emergency food, shelter and warmth.
Take the time to learn how your vehicle reacts, feels and sounds so that you know what normal is. Go with a group a few times when you want to try more than you are comfortable with so that you can really find the limits of the vehicle (and your intestinal fortitude). Once you have done all that, you'll know what you want to change about your vehicle. (which is when you start to understand why jeep stands for Just Empty Every Pocket!)