Agree that there would have to be some kind of visual cue of the presence of landmines.. But a fence and sign would be a bit too much, lol.. A freshly laid minefield is pretty obvious in itself, with the patches of disturbed ground in a geometric pattern.. That would make for a more subtle cue, would be more realistic, allowing for observant GV'ers to notice and avoid, while still blowing up the dimwits! Signage and fences appeared after the battle was over, so units transiting the area could avoid the danger, until they could be fully cleared..
People using mines to grief the game.. I suppose there will always be dikheds in a game like this.. But there were solutions to that in real life too..
Some battlefields of WW2 were mine infested.. Before the introduction of mine clearing vehicles, the solution was artillery, to blast a path thru, and follow with engineers, and it worked.. Most mines would be detonated by the concussion, and it would trigger any boobytraps left for the engineers..
Unless you were the Russians, they would blast the minefields with artillery, then march an NKVD penal unit into the gap, and just take the casualties
..