I like the FF solution best.
I wonder though, whether in absence of that, or combination with that, when someone mentioned ambushes, whether maybe annoyance-level defensive strikes might be the answer. You walk through a completely hidden archer's tile (or someone with drill), and you may get several potshots against you, however they won't stick around to "fully" engage you in a combat. Again, kind of like using first strikes, and then going to ground once you're out of first strikes.
Still makes a non-drill having legion of melee troops sitting there complacent as an enemy stack walks in and pillages the tile they're standing on, but I guess that means they have to move a tile away, then move a tile back in to "attack", oh well, active defense and micromanagement of same.