Pcad, until they disable moving phones, try a Dinotte double (400L) taillight, or for way less money, get a MagicShine and make a red lens for it, then strobe it. You'll be pleasantly surprised at how you can get drivers' attention when they are 100-400 meters behind you ( in broad daylight), and you give them time to relaxedly calculate how to pass you, and everybody is happy. A really bright tailflasher works to wake distracted drivers up. It's not totally amazing because hwy crews have been using strobe-flashers for years, but Dinotte guys were really insightful to apply the concept to bikes.