Me and a buddy did this more times than I can count at a past job. It was my first professional experience felling trees, most of which were long dead oaks and live hedge. We were both pretty inexperienced in tree felling, but I grew up on a farm and was good with a bucket loader so this is how we often did it when the lean looked questionable. The tractor was the newer equivalent of a 4020, and didn't have a cab (though IIRC, it did have ROPS). My buddy would cut the wedge and most of the back-cut. Then I'd drive in there with the bucket raised all the way, engage the diff lock, preload the heck out of the tree and stomp the brakes. Then he'd finish his backcut and over she'd go. I worried about falling branches, and was always gentle as could be when pushing, but still, we're darn lucky nothing bad ever happened doing this. My worst nightmare was having the hinge break, shoving the tree off the stump, and having the darn thing come back at me. Thankfully, that never happened either, but I've seen enough goofy stuff with trees that I wouldn't do this anymore (especially with long-dead, potentially rotten trees).