It would have to be on the side of the body to be technically legal.
The vehicles I'm familiar with are 92" wide and 13' 6" tall, however, the fancy new LED technology we use are single diode 3/4" round lamps with no reflection. The old incandescent lamps had reflectors in the lenses. In other words, we're not exactly legal but also have about 30,000 vehicles running around like that from coast to coast. The other 30,000 vehicles still have reflective lamps. With those technicalities aside, we do adhere to red/white side reflectors, red/white rear reflectors and top rear corner 12"x12" white reflectors.
It really depends on who pulls you over. They generally don't have the manual memorized simply because it's very confusing and there are TONS of loopholes. It's not hard to win a case if you're willing to argue some facts. You're on the right track with arming yourself with the DOT manual!
"There's nothing like waiting and getting exactly what you want."