This is a proggress viable setup that i personally used when breaking into C2.
The general strat i use for pretty much any map is 2PDT per lane, 2Flamethrowers per lane (3 if DU allows or more is needed), 1 Spike Blockade per lane and a Skyguard tower where ever needed.
Info 1: The Skyguard here is pretty pointless as i tend to focus mid/air lane anyways. At the end of my first clear it did only 1mil damage over the course of 5 rounds. You can opt to just remove it and use the 70 spare DU wherever you see fit, just make sure to take extra care about the fliers.
Whenever possible i place all the "Flamethrowers" and the "PDTs" on ledges out of the main path of the enemies.