Hmmmm... Okay, I seem to have a problem here. I tried to make invisible farms with various map copied buildings over them: bridge tops, outposts, houses or barracks, or a mix of those buildings.
The success varied every time I played the scenario: Sometimes there was only one farm tile left, sometimes the whole farm was visible. Those different results occurred anytime I clicked "restart" - I never knew what I would see when the scenario began. Sadly, I neither managed to get rid of all farm tiles during my experiments.
Cknchaos and Philip, does your version of the trick work reliably, and does it remove all of the farm every time you start the scenario? Is there any special other building to try, or a certain timer? So many questions... did you get to write your article yet, Cknchaos? Ingo