The double-bill headliner shows I've been to have worked this way. Opening artist will play about 30 minutes. The co headliner would play around an hour, and main headliner would play around 90 minutes. BUT then again, all of those tours were Def Leppard and they had to play 90 minutes. Depends on when it starts, I know most outdoor venues have sound ordinance curfews in effect at 11pm local time. So if the show starts at 7 as ticketmaster states, then opening act may play to 7:30. Give 25 minutes to get read for the next, they go on stage at around 8pm. Play 75 minutes, start tear down and preps for last band at 9:15, give them about 30 minutes, the last go on stage at 9:45 and play til 11. So I would say the Goos and MB20 will play about 75 minutes a piece. They could play closer to 90 if they had no opening act. They could both play 90 minutes with an opening act if there was no tear down time to prep the stage for the next band. So 75 minutes is my verdict.