Here's Halo Mini ... http://www.halobelt.com/halo-mini/
We bought one of these Dog-e-Glow collars from Petsmart today. On sale for $10 (halloween clearance). It works great. It's 3/4" wide, and 14" long. Only 5 LEDs (eg, 1 every 1.5 inches) for about half the collar (rest is buckle & battery). Blue light is easily visible at night. But Buddy's floppy ears do cover half the LEDs when his head is up. But a hanging Glo-Bee fixes that. Perhaps another (1 or 2) Dog-e-Glow collars stretched along the back of his harness would be ideal.