Tow trucks back in the day Didnt have any standard light bars.
The most common were old headlights mounted on a bar. or a stout timber 4 X 4. ( sort of like a roll bar. )
The headlights would either have red or amber lenses and somtimes were left with clear lenses. ( so you could see at night ... like spotlights . )
But there are examples out there that had the red "bubblegum machine " type.
so in the end whatever you choose will be prototipical.
If you go the headlight route may I suggest headlights from an old ford ( say 1920's to 1929 )
love what youve done. the gold on black is classic.