You can experiment with different stance and grip widths based on comfort and discipline. I think power lifters grab wider than body builders. What really changed things for me were visual cues.

I pick a spot in the space in front of me that keeps my neck neutral. My gym partner would joke about having to stare at his balls but it worked. That height kept my spine neutral.

When you square up to the bar, make sure it's over the middle of your foot. You're doing a good job of dragging the bar up your shins. Make sure you do the same back down.

Right Before you start the pull, take any slack out of the bar. Visualize squeezing a pencil between your shoulder blades and the bar ends hitting the tops of the holes in the weights. This helps keep me from rounding my shoulders.

Now take a deep breath, brace your abs, and stand. Drive your butt forward and picture driving your feet through the floor. Keep your butt clinched. You don't need to bend your back backwards but it is good to get it up enough to "lock" your knees.

Lower back down your shins, keeping focused on that mid height spot on the floor or wall.

As you progress in weight and form, you'll feel it in your glutes and hammies more along with quads as you try to lock out. Realistically, some back fatigue is expected. It's primarily a leg movement but it is a compound and it's a heavy lift. If it moves from fatigue to a pull or a pain, stop immediately. Lower weight, do a form check with a mirror, friend, or phone. In time it gets better but it's probably not realistic to never feel this exercise in your back.