Trunks has never been a 'soldier' so he doesn't know that trick. He's not usually one who lingers in the shower anyways, but his longer hair does take longer. Maybe he should cut it...

In any case, he's not far to the locker room for his normal gear, then to Sleeper 2. Shower and cleaning up, checking in on some people, then off to the quiet Car. Shouldn't be too hard to find Cassie, even if he wasn't sensing her ki.