Vince, unless you are dead set on an LED light, consider the light below. It is a 12V fluorescent, 8 watts, watertight tube, hanging hook and 15' cord for less than $10. They claim it has the brilliance of a 100W incandescent bulb. Plugs into the lighter receptacle of your ATV and should be easy on battery. At worst, if you run the battery down, I suppose you have a kick start. You could hang two of them with the addition of a double lighter plug adapter wire.
http://www.wttool.com/p/6619-0070Boone