Well, if off-road is your goal, I'd actually just start with more aggressive tires. Those will actually get you farther than locking differentials
2016 TRD OFF-ROAD
How is the spacer lift working out for you? I've heard it will damage parts overtime due to incorrect vehicle geometry. Keep in mind my truck is not lifted and I have very little knowledge on the subject.
2016 TRD OFF-ROAD