Best MPG 53' Dry van

Hi,

So many brands out there....which on will give the best mpg? I know everyone says good thing about great danes, but are they heavier then the others? I'm looking to buy something used and want the best MPG possible and prefer a lighter trailer so I can haul more.

Of course I can add side skirts, tail cones, low rr tires etc. But what will give me the best mpg before all that.

Also, some trailers come with roll up doors, but most have swinging. Is there an advantage to one or the other? What aboutt he number of latched on swing doors. Some have 2, others have 4. is 4 really necessary?

Thanks