It is irritating scenarios like this that me make hate IDPA at times.  People complain about our lack of rules, but they fail to follow the ones that we already have.  Hell, if we can't seem to follow the "clear and concise"rules that we already have, this new rule book should be a hoot! 

It should read something like this:  "You can engage this target from here, but not from here, however, you can engage it from here, but don't go past this illegal fault line that is not allowed per the IDPA rule book or you will receive a PE because the COF says so. BTW, you can shoot this on the move because it's a drill, but you aren't required to be moving if you shoot it from low cover, but if you do move, don't move too slow or too fast. You may also reload in the open, but only if you go to slide lock and you must use cover when shooting but that same cover is not really cover because you are not allowed to reload behind it. Actually, come to think of it, some of the other guys did it that way, but you can't 'cuz they beat my time by a $hit-ton and we are out of hot dogs. Any questions?"

At the signal, engage the targets when visible from within the shooting area. It really can be that simple.