There’s a really slick setup you can get at an arborist supply called a fiddle block. It combines the pulleys you’ve pictured in a pre-strung unit, allows you to move the entire pulley assembly to a comfortable pulling height, and allows the person doing the pulling to stand at 90° to the direction of fall, placing them out of the line of fire for the top and any material that carries in that direction once the tree hits the ground. It’s amazing the amount of force you can exert. Our crews use them a lot at work. The only down side is they are pretty pricey. But if you find yourself doing more of these jobs, it’s a great piece of kit.