First, I disagree that leaning is a function of seeing or not seeing your distance. It’s anticipatory either way it’s just that it’s uglier and more obvious when you miss.
Another of my favorite Woffordism is to “do the opposite mistake” which is to get left behind. Over a small cross rail intentionally try to get left behind. One of two things will happen 1) most likely you don’t actually get left behind but do what with your upper body. 2) You do get left behind and for some reason “finding” the right place between the two mistakes the next time is much easier.
Another way to think about it is to lean slightly backwards as you are approaching the fence. Again there is a good chance that what you feel as being your shoulders behind your hips is actually your shoulders over your hips. Sometimes we need to identify where vertical is before we can identify the feeling that we are more forward than vertical.
Or just tell yourself to pull your shoulders back and sit on your pockets and wait for the front of the horse to rise up to you.
Years ago Jimmy Wofford had the opportunity to watch all the riders riding slow motion over each jump at Rolex. (As a part of his announcing gig.) Afterwards at a clinic he told us that in terms of nano seconds the Brits and the Germans were the best and waited the longest for the horse to lift his front end before they fold their bodies. Most fascinating was that Jimmy saw a correlation between horses doing a better job bringing their front legs up and having them even in these European riders. The horses of the American riders who were more likely to be folding slightly earlier in the jumping sequence were more likely to have their front legs uneven as they rise and come over the fence. The upshot being that leaning and being early really DOES (Edited that!) have a negative affect on your horse’s physical performance over a jump.
To clarify: Leaning and folding early are not exactly the same thing, but they feed on each other. Most people that leaning also fold too early, but folding too early can be an issue without the leaning.