ya sounds about right, I had a second set of fogs on my nbs hooked up that way with a switch hidden under the dash that were set to be on whenever the key was in the run position but could be turned off also, wouldn't be hard to do I would probably just hook them up that way and disconnect the factory harness, I will have to get under there and see what connectors I need I may already have everything in my tool box.I guess a really simple way would be to run a new set of wires with a relay. Tie the relay to the 12V(on the DRL)
12V to the Switch pole on the relay
12V constant on one pole
Bulb +Red line to the other pole (two lines one for each bulb)
Bulb -Ground to a suitable ground (at each bulb)
Only down side is you can't shut this off(unless you run a line to a switch in the cab.)
There is Probably and easier way...