Too complicated and too fine-detail for me, thank you!
I don’t see hexes and units as a set size. A ‘machine gun’ token could be anything from a single literal machine gun or it could represent that the unit is a whole company heavily armed with LMGs, etc.
Even in regular infantry units, the reason you get more dice at closer ranges is part of that abstraction. It’s not just that the infantry shooting at the tank are more accurate with their rifles, its that they’re able to use more effective tools at close range. So ‘anti-tank gun’ might include sticky bombs right up to howitzers.
I can completely understand wanting to change the rules if you want the scale to be set and you want to add more detail though.