1. Use two splits so you can tower stack hermit and guardian towers in the same spot (might be able to substitute guardian for apprentice lightning towers?) All of these towers are on top of the bridge, not the floating path.
Use an upgrader adept, if you have one, to upgrade all of your towers and minions at one time.
Placed a summoner with two huntress guardians and a summoner with two squire guardians under the bridge for armor farming.