i ran the brightest and put a relay with a resistor draw hooked to my brake so it just blinks when i am on the brakes. i put the two bottom on first and then the top. i think i could got away with just one below the rack.
you can really see the difference from the original to what i have now.
you can barley see my tail light. when my wife was behind me all she could see was my jacket so i added some lights. now no one tailgates me. and people tend to switch lanes so as not to be behind me when i stop.