When your Speech is at 40, go to Camp Golf near Lake Las Vegas and accept the quest from the sergeant. Agree to O'Hanran's method and convince everyone, with Mags being the last one. After convincing Mags to play nice, accept her method and go to the gun range to help them with their guns (45 skill required). Wait for them to start walking back to their tent, then talk to Razz and ask about squadmates. The speech challenge will be there. It will be easy to unlock the "Outstanding Orator" trophy, as well as experience points in increments of 40. When done, talk to the sergeant to complete the quest or talk to O'Hanran and ask about the squad.