Best tracking device is a bigger gun and the "high shoulder shot".
Folds 'em up like a wet card table.
Having gotten the smart-ass out of me . . . I've heard guys use any portable fluerescent(sp?) light and it works great. You can find them at any WalMart type store in the flashlights, camping, or hunting departments. They are easy to spot, their the ones with the "tubes" for bulbs intead of the regular.