Phil
well you removed the most obvious and best answer , distance , but we all end up there , tight hooks , and elbows are very dangerous tools , when used correctly
but the are still based on body rotation and torque '' a circular engine ''
though in the hands of a skilled person that circle is very crisp ,
for it still comes down to cutting off the power side . the beginning of the circle , before it has developed momentum,
it's a feel thing , or a recognition thing , when you spend time in the clinch area / body to body . you can feel when a guy is about to fire and zap him or stall him of jam him at that moment , stop his mental and physical engine , he will have to restart this is the opening when he is at his weakest .

as a visual concept if you shut down the jab line or lead side of the body by closing in , he will either fade out with good footwork or rip in the rear hand ,'' baring a elevation change ''
so if your aware of that rear threat you just close it off as you move in, take it before he can shoot.

but these things require spending time in that environment and eating shots , not on every ones menu