My point is that poor AI nightvision is an axiom of your mission.... Work within the game's parameters - you'll end up with a much better mission than if you try to bend them.
I had to look up the word "axiom", but I tend to disagree with you here. Poor AI vision is just an axiom of OFP in ALL cases. The bastards can't see past their own noses, it seems at times. This can be fixed by changing the game's config (like the next ECP will do), or changing an addon's config, but there isn't a whole lot you can do as an editor.
The best thing you can do is to change the skill of the AI. Their skill directly affects how far they can see, so setting it to the max will let them see the farthest possible.
You might say, "but I don't want them to be that accurate when shooting!". Well, this is a valid complaint; however, there is a GREAT way to get around this. Using the 'setdammage' command, give them NEGATIVE health:
this setdammage -1
The lower the negative number, the more 'wobbly' their aim becomes. However, I suggest you set it between -1 (0% skill) and 0 (100% skill). With BIS weapons, this results in more "dispersion" between shots than normal, which makes firefights last longer. If the weapons you are using already have fairly high dispersion, then you might want to make this range smaller.
I've used this method and I'm convinced it is the best workaround. As soon as the unit is hit, he will go to positive damage (as if he were at 0 the whole time), so this doesn't end up giving units "more life". If he gets healed, he will go back down to 0, which is the main flaw.
I swear to god this method is so useful. I think everyone should use it. Try it and see.