Having the right size sand anchor. This is my home built MAN size well Truck Size sand anchor which will be used on our next trip. (We really hope we don't need to.) The winch that will be hooked to it is 20,000lb. and mounted on my Canter 4x4. The base plate 600x500mm (24x20") is 5mm (3/16") Bisalloy so shouldn't bend, upright is 100x50mm 6mm (4x2" 1/4") box section 760mm (24") long. The pull bar is 75x50mm 4mm (3x2" 3/16") 1300mm (51") long. And yes it has a few adjustments possible so we can change the angle of pull if needed. I zinc plated it as well.
Reading through the thread, it sounds like most things have been covered. The only thing I would add is pretty specific to your location and where you'll be. Where I'm located, there's little-to-no cell coverage as soon as you leave Las Vegas and head into the desert and mountains. So, I always bring a satellite phone with me, which also has SOS GPS location capability. Since I tend to go out solo, this is my "in case of emergency break glass" tool.
X2 on the smittybilt strap. When I got mine, I was all pissed off. So I tried to kill it. IT IS TOO TOUGH. Cheap, multipurpose, and durable. Also the price is right.
So that, 3 shackles (because you always misplace one) and go from there. Beyond that, I carry a small folding shovel. More for use around camp than anything else. I've started carrying four 8"x8"x12" blocks of wood. Easy to use if you get high centered on your diff, or need to build a temp ramp up a ledge or something. Cheap and handy around the garage the rest of the time. Oh and bottle jack YOU NEED A BOTTLE JACK. Works so well.
Beyond that, I really like my SEO 30ft kinetic strap and soft shackles. Work very well and handy. But that is the equipment I mainly use.