I modified the Info file to make it work together, but I haven't found any problems yet.
Landfill cannot be undo and cannot be redo,but the same is true for floor tiles, which cannot be manipulated by this mod originaly.
So, what is conflicting?
Last I checked, Landfill Plus has a bug in it's code that crashes when you undo entity placement or redo entity deconstruction, and I can't do anything to fix it on my end. It has nothing to do with the landfill itself, it's just the way their mod is currently, and it still hasn't been updated, so I'm inclined to believe that it's still not fixed.