Event based stealth system?

Sorry if the title of the topic isn't very specific but it's the only thing I could find...

Anyway, my hero is now imprisoned but an ally helps him escape from his cell and now they have to prison break. Problem is, there are plenty of guards patroling around and if they're found they'll have to fight hard.

I was thinking of inserting these patroling guards in using simple events with fixed move routes and a Player Touch trigger to process a battle, but it looks a bit unrealistic to me that the guards will notice the escapees only from a tile away...

Is it possible to trigger such event at a distance of a few tiles instead? This prison map is made of very narrow corridors (1 tile wide only, except in a pair of spots where it's 2 tiles wide) so it's not a widely open space where guards have to look in all directions but instead watch what's happening in front of them only.

Or is it possible to make the trigger zone of the player wider than a single tile without messing with the core engine?

Try this tutorial :

http://forums.rpgmakerweb.com/index.php?/topic/3452-direction-based-line-of-sight-events/

Your can find a lot of great tutorials for VX Ace in the forums.

Yanfly's event chase would help with that. You could set it so that they will chase you if you get within 2 tiles. Only problem is it will not reset them back to the original location, so it might mess up the patrols if you run far enough away to lose them.