I know there is already a massive discussion around this topic, but I had an idea this morning. The "Large Artboard" that is now available as far as I can tell is not truly a new massive artboard. It's just doing 1:10 scale math for you automatically. I see underneath the hood when using my vinyl cutter for example. A file sent to the cutting software sees everything at 10% size. Another example is when copy/paste from large artboard to a normal board, it will come in at 10% size.
Here's my suggestion: Instead of having a single large artboard option, what if we could just set the scale we need to work within the 227" limit. If I could set my scale to 1:100 then I could build my banners at "full size" but in reality Illustrator is just doing the math for me.