negative lock pulse to for remote start

I see your point. If I found the 12volt lead to the lamps and not the switch could I use parking light lead from the remote start and diode isolate the cargo light leads? (So they wouldn't go on when I hit the normal parking lights) -Rog

Yes, exactly.   That will do it.  Only caution is the current draw of the two circuits.  Most remote start units parking light output can handle 10 amps.  Double check yours.  If your truck needs more for the combined circuits, then a relay with a fused & dedicated 20 amp source might be required.  Also 6 to 10  amp blocking diodes would be necessary.Soldering is fun!