If the good Captain starts a turn with stress and then executes his maneuver (and it is a green one) and then collides with another enemy ship can he take another stress and take another action from the dauntless title?

No. The title triggers after executing a maneuver, which is before the check stress step. It's the same problem Night Beast has.

Yep, you've got to start the maneuver unstressed to use the title.

So against a pile-up its better just to take APL then.

That would be the best option.