LPhillips,
I hope you know my post was made in jest. And yes I realize anti-air cannons can point in other directions (the German 88 mm AA gun being co-opted for their Tiger tanks being the most famous example). But in that case those cannons would be useful against land units too, not just flying or water walking heroes. Plus we can consider the defensive wall bonus to be cannons given that it works against fliers
In version 0.9 when neutral Orcs/Wolfriders/Ghosts get their ambush roll the entire problem can be taken care of by placing 2 Orcs in every neutral on this map. That threat of instant death will keep lone heroes from attempting to conquer on their own while at the same time being weak enough to not stop masses of regular armies from conquering the neutrals.
KGB