I've just picked up the GM Toolkit and seen the optional rule suggesting a character could take a second manoeuvre for free instead of using an Action. However, seeems to me it's already more favourably covered by the Perform a Stunt or Assess the Situation actions.
1. Perform a Stunt - if the stunt is "sprinting", use Athletics skill, on success gain an extra manoeuvre, on 3 successes perform 2 extra manoeuvres. A single boon recovers 1 Fatigue, so you might as well pre-emptively spend it on another manoeuvre. Result = up to 4 manoeuvres in one round for zero fatigue outlay.
2. Assess the Situation - spend 1 extra Fatigue on 1 extra manoeuvre, use this action card to then recover that 1 Fatigue investment and gain the equivalent of 1 Defence as well. Result = 2 manoeuvres for zero fatigue outlay, plus 1 misfortune dice to incoming melee and ranged attacks.
With one option for Strength and one for Intelligence, it strikes me that there aren't going to be many characters who would need the option of Action=Manoeuvre. Though obviously, throw the odd challenge or misfortune die into the mix and things change slightly!