A 20 ft recovery strap is good to have: for getting your truck or someone elses out of a bog; also for securing winch line to a tree without damaging the tree.
A small pack with all usual gear for surviving: knife, fire, batteries, food, water, tarp, spare socks, wool cap, poncho, whatever else you like.
Drinking water and food in the pack or under truck seat. Like they teach you in Ranger School: 2 cans of tuna-in-oil at the bottom of your pack will taste like filet mignon when regular grub runs out and you're really hungry in the backwoods.
One can of inflate-a-flat and a 12 volt air compressor that works: can save a lot of time and trouble.
A plastic tarp for general use, or overnight shelter if your get stuck or broke down, or for putting tire chains on. Can also be handy when combined with sticks and rope to make a field splint on a broken limb (hopefully someone elses...). I recommend the "sportsman's space blanket" that has a silver side and a colored side: these have fiberglass reinforcements every 1/2 inch, last for years, good for keeping a child warm (and visible) if it starts raining while you're loading those heavy rounds, plus they seem to dig having it like a tent. Also nice as a picnic blanket if the misses is along on the trip. Beats sitting on wet ground. Or if you're covered in mud and sawdust, you put in on the truck seat to keep the upholstery a tad cleaner.
And always park your rig further away from the tree than it is tall. 'nuff said.