There's only 5-6 spots you need dampeners on swamp.
Two on each end of the bridge (pictured in screenshot below), one on the side of the conduit ramp leading towards the bridge, one on the inside of the bend leading up to blue, and one at each base. Anything beyond that is superfluous.
This setup is pretty much as efficient as you can get dampener-wise. None of them overlap, and if you place them juuuuuust right, their footprint doesn't interfere with any other emplacements. Also, the only dampener that ever gets hit by burst transmitters is the one at the end of the bridge closest to the green base (the right dampener in the screenshot).