My main strategy for this particular game ended up being to try and optimize my placements while conserving resources to apply to new routes that come in as they appeared so I wouldn't be left too wanting later. I did end up placing units farther out from the middle but there was a little bit of grouping later on as bat spawners came around and I needed an archer or so close by to keep things safe.
I will follow you on here and keep an eye out for more of your games!