I've "been there", and right in my own front yard too. LOL
If it is as bad as it can be... then "sticking" wood and rocks at it isn't what it will take to get it out.
You may have to dig enough in front and/or behind the tires to lay down a flat solid surface that you can drive ONTO, as opposed to drive UP to.
If there is any slope in the terrain at all, go for the low side, so gravity helps you get onto the new surface.
And wood isn't much good for traction. Maybe concrete blocks.
Don't try to move it again until you have a perfect "runway" installed at each tire for it to build a little speed on.
There are now timbers in my front yard that no living soul will ever see again -- a good foot below the surface! LOL
Now... there is an other method, if you have a jack. No, not the kind for lifting a car. A jack to lift a bus. A "5 ton" jack or bigger.
Use thick plywood and whatnot as a base for the jack, and jack each wheel up high enough to build your "runway" above ground.
Either way, it could take you a full day of hard work. But it can be done.