Try:

Pelican 2630 (1 W and 3 AAs) or Pelican 2680 HeadsUp Lite Recoil LED (1 W and 4 AAs).

2630 has battery case mounted on the back of your head making it slimer and 2680 incorporates them into head of the headlamp making it bulkier but good for diving. I use the 2680 for night diving and it is amazing.

Whenever you use something with AA batteries it is going to be bulky and heavy.

Somebody suggested Petzl E+Lite. Good light that can be used in emergency and batteries take very little space. Not a big light and not the most powerful but great addition to kits becasue of its size. Also them batteries hold charge for a long time.