I’m 6’6”. My bench height is 42-1/2”. I cannot fathom working at a lower height. All those rules about knuckles and wrists are for regular sized people. The human body is nothing but a collection of levers; primarily levers where the fulcrum is at one extreme end. The longer the lever, the more force is required to lift something against gravity at the same angle as a shorter lever. The force in this case is your lower back. If you are 5’9” go ahead and spend the entire day working with a 30 degree bend at your back. But at my height? Forget it. And at 6’10”???? that’s asking for back surgery down the road. At extreme heights you have to convert all these rules to be compatible with tall people levers.

Raise the bench height if you can. More importantly, wear a back support like what those folks in warehouses use. You can find them at any home improvement store for about $15. I keep one in my basement shop and wear it all the time when woodworking. With it I can go all day every day with zero problems. If I forget to put it on I will know it after an hour. Tall people have to treat our backs differently. I don’t like the shoulder strap on my back support so I just cut them off as I don’t see any need to undo it like warehouse workers frequently have to do. Bonus hint: for those horrible plane flights, put on a heat wrap and then put the back support over it as loose as you can get away with (under your shirt so you don't look like a crazy person). I learned that trick from another tall flier and it was a game changer.