at 360 overnight queue'rs were let in under the stadium so depends on how the security feel i'd guess.
Times may have moved on. I live close to the stadium and get a community newsletter from Croke Park before each concert. For Springsteen in 2016, it says, inter alia, "overnight queuing/camping will not be tolerated". The newsletter goes on to say that stewards will be on duty from the evening before the concert to deter queuing/camping in the community area.