Boblou,
First, if you are at a beach you would be surprised how little you need the light. I usually have enough light to see where I am going and where the water is. It is harder to keep a good hunt line going.
When I do need a light to look at a ring or something interesting in the scoop I have an LED headband light. Plenty bright enough and as pointed out by another poster, can be gotten at a low price.
I have never had this problem but I have heard stories of people being harrassed at night by drunks and others. One guy I know was even stabbed and his detector was taken. I usually go with a buddy when I night hunt. If I go by myself, I can usually count on another person detecting being there. I will go up to them, introduce myself if I do not know them. From then on it is kind of an unwritten law that we keep an eye out for each other. I did notice one detector that seems was getting bothered by three other people. I tossed my long handled scoop up on my shoulder for all to see and started moving his way, detecting as I went. My main concern was, If he had been attacked and I hit a signal on the way to help, should I
A) Dig the signal first.
B) Mark the signal and come back after helping.
C) Forget the signal and go help right a way.
D) Dial 911, report it and let the police handle it.
E) None of the above.
I will say, some of my best times hunting have been at night. Nothing like the moon shining off the waves or having the waves light up from plankton in the water.
Good hunting.