make towers do max hp% true damage then rework ARMOR/MR/HP the way it should be.

You dont. You just die and get ready for the next game and ban that shit.

I like the idea. Make towers deal around 12% to 17% to champions only as it scales upwards. (Current damage on minions stays of course, though they could set it for specific minions too.) This means full health champions without shields or healing will always take around 8 shots from full health before dying to a turret. It beyond enough to keep divers effective from lvl 1 to 18 while removing this sense that towers are fucking useless.

Players within a short while will gain the sense of how much they can take during any dive, and how much they can take before needing to swap aggro.

If this doesn't seem damaging enough, let Riot increase that damage by 1-2% until they hit that sweet spot everyone's more or less happy with. If it seems like too much, lower the damage. If after half a season this just doesn't work out for some reason, change it back.