I currently own a V nose 20ft enclosed trailer and have owned the same size in the traditional front.
If
there was any difference in fuel mileage I haven't detected it. It is
usually grossing near 7000 lbs and is pulled with a 96 F350 Powerstroke
diesel that weighs right at 10,000 lbs.
My gut says the V nose should return less drag, but I'm not convinced real world delivers it.
Several online sources indicate there is no advantage to the V nose aerodynamically.
I liken it to the tailgate down effect on pickup trucks. Many will swear they get better fuel mileage with it down even though several wind tunnel tests have proven it actually increases drag when down