Forget the first down - direct snap it to the fastest, most sure-handed player on the team, and tell him to run around anywhere but his own endzone until he sees :00, then hit the turf, and keep two hands on it. You can't tell me your KR can't avoid being tackled for 5 seconds when there's no requirement that he gain yards. Heck, if he runs straight backwards, it would take at least 4.3 seconds for the fastest player anywhere just to get to him, assuming an obstacle-free, straight-line, no-pads sprint to the endzone. Get the ball, turn around, run as fast as you can to the far sideline at your own 1, with a convoy blocking for you. You can easily kill 5 seconds that way.