Here on the farm I've sunk every tractor & combine I have, usually several times a year. My problem is being alone, finding drivers for the multiple pulls..... Learn to drag them out a foot at a time with one tractor....
We typically go series, one tractor in front of the other. Trick is the rear tractor gets a lot of pull, that first chain needs to be strong, and you can chain the front tractor to the hitch of the rear tractor - not pulling through the rear tractor, but from the hitch frame.
If folks driving are not used to clutches & tractors, the danger is popped clutchs, broken chains. We put a car tire in the line, it acts as a shock absorber.
No point in trying to pull in reverse, you will need all the traction you can get, tractor tires are directional with the angled ribs, you will need to pull forwards to get anywhere.
There are many, many safety issues with breaking chain/ cable, tractor front ends rearing up, bending or twisting frames, etc. One fellow a few states over hooked up 2 tractors to his newish $200,000 green tractor, bent the frame of it. Shot himself over it.....
Anyhow, be safe, too many issues to cover, but typically out on the farm we hook up one tractor behind the other for tis type of work.
--->Paul