I haven't actually played your mission, but in regards to people "flying by the warp interact". I'd highly recommend placing an invisible wall tall set at -20 Y that stops people from accidentally flying out. When you drop out of warp you set the wall to disappear. That way you eliminate even the smallest chance of the person overshooting.
Thanks for the suggestion Nagorak. I'll take a look at that, although the larger invisible object seems to be working too.