@Forest_Man Don't know your area, or what materials are available locally or if you have freeze-thaw stuff, so I'm gonna try to be as General as possible;
Step 0; get a string line, tape measure, and marking paint, maybe some lathe, and lay out the drive
Step 1; strip organics and add a way for water to get off the subgrade
Step 2; 'box out' the base area; 12 ft wide is a good number; but cut down maybe 4"; only in the roadway, roll, or track everything in well; remember you can't pack mud or dust; some moisture is good, too much is bad. If anything is really mushy, cut that out and add decent fill
Step 3; add whatever the cheap base material available locally; to get it back upto grade; roll/pack
Step 4; seed any slopes and ditches, to prevent erosion getting out of hand
Step 5 (optional); finish grade, roll, and if you want a 'pretty' top lift,
Define your goals; if pretty isn't one of them, or even smooth, but 365 day access is the goal; you might be able to get by with cheap dirty rock, ball field clay, ect
To do the dirt work portion; if it's longer than maybe 500lf, I think your gonna need more than a 3 point attachment; but spreading base can easily be accomplished a box blade as long as you get the dirt work done.
Although not ideal; you could simply add gravel/rock/base to that subgrade; 100% over the next few months it will sink into the mud, but you can get it passable, and you can add additional rock/base as time goes by. People often want a one time solution, when really just ordering 3 loads of base every 2 years isn't the worst thing in the world. You will want to stop water crossing the drive,