These would be more effective at controlling choke points if they are placeable on shallow water and maybe even marsh tiles? Just something for you to consider .

I don't find this solution entirely logical. Placing poison-coated spikes in the water seems questionable to me. Especially since visually, the spikes "floating on the water" wouldn't look very appealing.

Basically, if you really want to, you could make a tweak mod, or even a fork of the poison spikes mod...

I wouldn't object to that. In any case, I've done the best I can with this mod, given my skill level.