Hmm. Interesting idea. This may work actually. But still, one mistake on the last level (that's where it usually happens anyway) and you are back to square one on that girl. I wish it moved you only one level back if you lose.
Yeah, I got a tactic that seems rather safe even with 10+ guards on the field. Completed 6 girls before making several mistakes in a row and spending all my tries. I make a trap with a width of 2 squares and then split guards and capture them in those traps, it is very safe to capture them with it. It is easier to make traps before splitting guards because there is a lot of space but it is easier to split them before you make traps because they take some space. So it becomes a game of balancing. Do a trap, capture a guard, do another, capture another one, split them to make it easier, make traps again... There is no random in this minigame, so I only lose because I hurry and make a mistake of underestimating enemy speed or by losing control (I started to hit my own tail a lot when I lost all tries today).For this event it makes it easier to isolate the guards on their own little islands and just work from there. only having to watch one guard makes a difference.
Almost a month left and 11/17 girls remain. Unless there will be 16+ guards on later levels it seems I may still finish it.