Eomer -
A winch rated for 1/2 tonne sounds a little light to me, for a van (even for a small van). At least here in the US, that size might be appropriate for a quad (4 wheel ATV) or similar. For a full size vehicle, 3 or 4 tonne rated would be more common. For a smaller vehicle, 2 tonne wouldn't be out of place.
If the vehicle is on a level, hard surface (with properly inflated tires), then comparatively little tractive effort will be required to roll it. But, if off track, as you've indicated is a concern, and especially if the ground is soft, the winch might need to displace quite a bit of soil as the vehicle is dragged back up onto the track. Even though most automotive winches aren't rated for overhead lifting, having one with approximately the same nominal line pull as the weight of the vehicle is cheap insurance (again, at least in the US - prices may be different where you are). Remember that the rated line pull of a winch is usually for the first wrap of cable on the drum (cable mostly pulled off the drum). As more and more cable is wound onto the drum, the effective diameter of the drum increases (cable is being wound onto other layers of cable) which decreases the mechanical advantage of the winch and so also decreases the line pull.
Many electric winches these days have plug-in remotes, which you can bring into the vehicle (if the cord is long
enough). This would allow you to operate the vehicle and the remote at the same time. At the least, you can position your meaty bits in a position of relative safety. A parted cable is a fearsome thing.
There are also hydraulic winches available which use vehicle's the power steering pump to drive the winch (for vehicles with hydraulic power steering). This style of winch may not be appropriate for your vehicle.
Another option to consider might be a manually operated mechanical winch of some sort. I now have accumulated several "come-a-long" cable pullers, with a ratcheting hand lever rotating a cable drum. At least two of these have "snatch blocks" permanently installed on the cables, and I have another snatch block which can be quickly slipped onto a line. Snatch blocks allow the line to be doubled, which can double the line pull force (give or take some friction losses, and at half the speed - you don't get something for nothing!), or can be used to redirect the angle of line pull. Though my cable pullers do occasionally get pressed into service for vehicle recovery, they get used a lot more for other purposes - moving/lifting heavy objects, pulling "leaner"
trees to the side so that they will drop somewhere more convenient, etc.
Another style of manual mechanical cable winch is the highly regarded Tirfors. I've never owned or used one, but they are commonly used for vehicle recovery, rigging, raising timber frames, etc. These winches "walk" or "inch worm" the pulling unit along the cable, but do not wind the cable on a drum. The available pulling force is constant, and these units can be walked along the cable in both directions. These can be had in models rated for overhead lifting, and there is no limit to the length of cable which can be used, since it isn't wound onto a drum.
An old fashioned style of winch, which used a drum but also didn't store the cable or rope on it, is the capstan winch. These were fairly common on the old Series
Land Rovers (Fairey was the standard brand), but I don't know of any current manufacturers of small vehicular capstans. Capstans are still quite commonly used in marine applications - deck winches on small sailing boats being a well-known example. You might find a marine capstan in a salvage
yard at a good price, though it may only be rated for use with certain kinds of rope. Since synthetic (non-metallic) winch line is commonly available these days, this is probably less of an issue than it would have been a decade or two ago.
For many years, I only had a manual Maasdam brand "come-a-long" cable puller style winch, some rusty chain with hooks pinned to the end links to extend my reach, and a couple of nylon sling straps. If on a tight budget, I'd go the same way again. This is a very versatile set of tools, not just for vehicle recovery.
You'll certainly need some sort of anchor when extracting a vehicle. This could be as simple as wrapping a "tree saver" strap around a substantial tree or driving some "pickets" (steel stakes) into the soil, or might involve burying a "dead man" in a trench or hole dug into the soil (anything from a length of log/timber to a spare tire, under exigent circumstances), to using a folding "Pul-pal" style plow anchor.
There are good "self-recovery" instructional videos on YouTube which discuss technical and safety aspects. A local "green laning", four wheel drive or trials club might be a good source of education in these matters, depending on your location.
I hope this is helpful.
Kevin