How could you maximize the number of 5 min miles? I like Whipp's suggestion of sessions and the noted need to warm-up and maybe cool down.
My guess as a competitive hobby-jogger is to not front-load this event. I believe cumulative fatigue, not matter how fit, will have a heavy hand in how thing shake out toward the later third of however this is broken down.
I think sessions are also the wisest way to go but the question is on number of reps and time between sessions.
Matt