>>535969983
With artillery you can automatically destroy nests in your pollution cloud, meaning that you don't even need a wall around your whole base, just around your artillery.
When firing they will aggro enemies from the nests they destroy.
Instead of one huge wall, you can have a few artillery outposts with turrets and walls.
So yeah you'll need walls regardless, but you can be very resource efficient if you want to.
I tried to draw it for clarity.