Daytime running lights are a safety feature, not to help with visibility. I'm all for anything that might help other motorist notice me an prevent them from pulling out in front of me.
The question is this; do have DRL's on the Stang is there a physical piece that needs to be added or is it just a option that is turned on by connecting to the cars OBDII and changing it in the ECU options?
In the meantime you could always put a piece of black electrical tape over the light sensor on the dash. (effectively making the car think its always night and hence your lights will always be on.)
I know many insurance companies offer discounts for having DRL's. For me its $13.35 discount over a 6 month span (not much but still something).