I didn't see anyone mention the obvious, but gears and lockers are the best traction improvements you can do.
With an open diff, as soon as one tire to lose traction, you're stuck. And when that happens, your vehicle then asks one tire on the other axle to do all the work...with a very high probability that tire will become stuck, too. Not sure how good/bad the VDC is, and whether it provides any improvement to a stuck situation (by applying braking to the spinning wheel to transfer torque to the opposite wheel), but there's really no replacement for mechanical traction. Even a limited-slip is an improvement (if you have one), but as the name implies, it will permit slipping...and Nissan has dumbed them down since the 02 truck/SUV line-up.
There are locking options available for the R51. There's a group buy going on right now, btw (expires in about 10 days?) for a Lokka for the front axle of your vehicle (R180) for $250, which is a great deal (use Path15 at Lokka.com, expires soon, use website to confirm fitment). ARB also has front and rear air lockers...not cheap, but very effective.
Gearing is the other factor. When you've increased tire size, you've decreased gearing efficiency for off-roading. Gearing options are limited, unfortunately, but if there are any, it'll require a decent amount of research...no one's making gears specifically for the R51, but the axles it uses have been used in numerous other vehicles for generations and are relatively unchanged.
The semi-obvious caveat to the discussion is the terrain you're on. If you are on very muddy, slippery terrain, even lockers and gears won't be your answer unless you have the right tires. DuraTracs are good, but still might not have the lugging you require on wet/soft terrains (I have DuraTracs, too). A mud-terrain tire would offer more traction in, well...muddy terrain....but really any terrain where it's necessary to claw into it vs. crawl over it. Airing down, as previously suggested, is also a good way to increase your contact patch for any tire.
Lastly, if being stuck in general is a concern, be sure to pack appropriately. Tracks and a come-along can come in handy, with a winch being the best overall option.