Make ranged auto attacks do 1 true damage to the target instantly and proc all aggro from minions
and turrets
This would give almost the same amount of risk that a melee champion has when auto attacking anywhere near turrets and minions while not completely breaking ranged champions from any given lane.
Also if you're wondering how this works, the ranged auto attack does one true damage as soon as it's thrown by some invisible laser or something and then after the projectile hits it does normal damage. If this somehow ends up being gamebreaking DPS, just take one damage from the regular AA.