Great topic! We frequently travel alone in back country areas, but almost exclusively on two-track routes, forest service roads, etc., and not all are maintained on a regular basis.
As 2dub pointed out above, the guy who said that knowledge is a key starting point is right on the money.
The first thing we'd tell you to add will not cost you a dime. A trip plan. If you're going out alone, have a basic document that details where you're going, approximate dates, due-back date, and information on who you are such as a current photo/physical description of you, description of your rig, etc. And leave it with a trusted friend with a "Uh-oh, he's not back" date/time to call the authorities (or friends with the know-how to come look for you). We used to do wilderness SAR and it is amazing how often people don't do this simple thing.
We don't have a winch and have (knock wood), never needed one even when traveling with other rigs. I'd definitely drop that to the bottom of priorities. Of course, we're frequently in desert areas and there are no trees to anchor to and the equipment to bury a deadman to anchor to is just more cr@p to haul. (And the time needed to dig a hole that big... well, not at my age!)
Food/water for 5 days. We also carry water filters.
Add a decent first aid kit and take the time to go through a more-than-basic first aid class. Recommend Wilderness First Responder if you can take the time for it. But even a basic Red Cross 1st Aid class would be great.
Add a set of what I call "pioneer tools" (USMC term), i.e., bow saw, shovel, hatchet and/or axe, small pick, decent pry bar, etc. We also have a small haul system, i.e., some pulleys and cordage, so that if we need to put together a mechanical advantage pulley system to move smaller stuff out of the way, we can. These are small, climbing/rescue pulleys and 9mm cordage left over from our days in technical rescue. So far as the other tools, consider your situation if a small tree falls across the trail after you passed by and that's also your exit route. You won't be able to handle a 4-ft-diameter Ponderosa Pine, but small stuff is easily dealt with.
A small tool kit is always a good idea. Shoe-box size. You can get a lot in that. Duct tape.
Agree with the tow/snatch strap, good tire repair/plug kit, and a better-than-basic air pump. We got the Viair 88P and are pretty happy with it.
We don't have traction boards, but have been considering them. Just a few months ago we actually buried the truck in deep sand and through airing down, some local vegetation, and technique, did a self-rescue. If the deadwood hadn't been handy, a couple of traction boards might have been useful. We keep reading good things about the less-expensive X-Bull boards.
We have small HAM radios and will soon be getting GMRS/FRS radios to complement them. We're also 'thinking' about a cell signal booster, but not in a serious way just yet. We often find ourselves beyond cell signal coverage. We like the idea of something like SPOT, just not ready to go there. Since we're sometimes in remote desert, we carry a military-style signal mirror, which works incredibly well for getting the attention of aircraft.
That's it for now. We are really interested in reading what other people think on this topic - never too late to learn something new!