[Fulltiming]

That would likely work as a stop gap measure. Without a diode, that would turn on the running/clearance lights anytime the headlights were on also thus defeating the purpose of the separate clearance light switch if you ever want to flash your clearance lights. If you are just driving the relay trigger, you will be pulling very little additional current through the clearance light circuit. If you are on the load side of the tail light relay, I would be more concerned about the load.