When I'm on the road with my tractor I use yellow flashing lights. There's a strobe on the front and a pair of lollipop lights relocated from the fenders running on an alternating flasher (like a school bus). I lined the forward lenses of the lollipops with foil so they don't shine into the cab.
Since the fastest my tractor will go is around 15MPH, it is for all purposes a stationary object to road traffic travelling at normal speed while I'm running at top speed. I live in a county with a large Amish presence and they get whacked with some regularity because motorists don't realize how fast they are closing on the buggies. Then there's the fact that I rarely use brakes with the HST anyway.
ETA: Using taillights only would concern me because with little or no daylight a car driver may mistake the red taillights for another car ahead of them.