I think you are missing the point of AirPower.In which case, you maybe missing the point of Airpower, it does away with zones, you will still have positional issues like you do today , where you are trying to charge your 8+ on one zone . Air power will not fix his putting the 8+ in the wrong position , part of the problem is the 8+ , it needs to be in the right position......u experience that issue today.
The problem you describe is exactly what AirPower is designed to overcome, with different charging positions of different sizes overlapping each other. The problem Apple is having is due to heat and bluetooth interference for the iPhone to communicate with the other devices to display their charging status.
Apple's proposed solution would allow you to put your iPhone 8+ anywhere on the mat at any angle.