Mike, with higher protein flours, tough crusts are usually a sign of gluten overdevelopment, but with a midrange protein flour like KABF, overdeveloping the gluten can be hard to do. As long as you are using a little bit of oil (2%ish), a little bit of sugar (1%ish) and a hydration that's not too far above KABF's absorption value (62-64%), then your gluten framework should be tender.
I don't think it's the dough that's tough, but the denseness of the final product that's creating toughness. It's like the expensive, almost impossible to scoop, premium ice creams that contain very little air. Air is critical to tenderness.
We've talked a little bit about maximizing volume/oven spring in the past. Here's a refresher.
From previous comments, you've made it pretty clear that you're not a fan of bromate. Unless you're getting along in years, you most likely grew up eating bromated flour pizza in Brooklyn. If you're still eating at non chain pizzerias in the midwest, you're most likely still consuming it. If recreating pizzeria style pizza is your goal, then you should use the flour they use- the flour that gives you the most volume with the least amount of effort. You're making your quest for recreating the pizza of your youth SO much more difficult by using KABF.
The ninth-century Buddhist master Lin Chi is supposed to have said, “If you meet the Buddha on the road, kill him.” The way I interpret this is: "You can't meet the Buddha, you have to become the Buddha yourself." No one can tell you how much yeast to use. You can get a rough approximation, but your environmental variables will produce different results so what works for one person won't work for another. It's up to you to watch the dough, recognize proper fermentation and fine tune yeast quantities in later doughs to hit desired time frames. You can't take a recipe, follow it to a 'T' and then be disappointed that the dough didn't rise enough/achieve sufficient oven spring. A recipe can't predict fermentation in every possible setting. You have to predict fermentation- and you can only do that through trial and error.
If you post photos of your fermenting dough, we can help tell you when it's at it's peak, but no one here (or anywhere else) can tell you exactly how much yeast to use.
Focusing on recipes while ignoring your oven setup is a little like a gardener going to tremendous lengths to combine ingredients for the perfect soil, but then failing to water the plant or give it light. Just like a plant can't become a plant without water or light, a NY style pizza can't reach it's full potential without the kind of conditions that you find in quick baking deck ovens. Nothing is more criticial to the pizzamaking process than a short bake time. Without a short bake time, oven spring suffers. An 8 minute pizza will never have the oven spring of what you grew up eating in Brooklyn. The only way to dial that bake time back is modify your oven or get a more conductive, thicker stone.
Summing up, in the past, you've talked a bit out the simplicity of NY pizza and your desire to emulate the pizzeria owners of your youth and not overcomplicate things. You can't get any more simple than bromate. NY pizzeria owners have been buying bromated flour for decades without a second thought. They may not know a thing about baker's percents, but, believe me, at some point prior to opening their establishments, they tested their dough with different quantities of yeast (and water) and learned how to both watch for and predict proper fermentation. If home bakers all owned deck ovens than that aspect would be incredible simple as well, but, since we don't, we have to get a bit nerdy about it. A pizzeria owner can be, for the most part, completely oblivious about their deck oven. With our thermally challenged ovens, though, we have to understand things like conductivity and thermal mass. Mimicking the effects of a $2K+ deck oven with a $500 home oven is going to involve some alchemy.