It may be a little off the subject but.
From what I have read and heard. The reason stumps take so long to Rot out/Decay enough to be popped out of the Ground. Is that the growing tree is cut down, it tries resprotting and continues "Trying" to grow for 2 or more years after the tree has been cut down.
So What I am trying is Kill the Tree first, in the spring, if it is not standing close to something that can be damaged if the trees should fall during a storm let them stand all summer possibly 2 seasons. Then fall the tree leaving a 4 foot stump, for leverage and try pulling/popping the tap root to remove the Stump.
I found a BroadLeaf herbicide at a Farm supply store , "Lamine 2-4 D" relatively cheap $34.99 for 2.5 gallon, and it has instructions for "Forestry Use". It refers to using a "Tree Injector" and injecting so many ounces below the bark, based on the Size of the Tree Trunk. I put a small Generator on a trailer and drove around to a few "Test" trees and drilled 1/2" holes 3" deep at 12 ,3, 6, 9 o'clock positions downward at an angle, bought a Turkey baster to fill the holes, and I filled the holes with the 2-4 D
I did that May 27th, The trees were in full foliage , after less than 2 months , not any more

, not a leaf on any of the Trees. Now I will wait til the winter, fall one of the test trees and try pulling or digging under stump with FEL in moist spring dirt to see if one season is sufficent or if they need to stand longer for the root system to decay for easy stump removal.
All that being said, if your are on a tight time frame and the trees and stumps must be removed fast, this process is out.