KPRA laws only apply to trailers longer then 48’. Most 53’ fixed spread axle flats have the rear axle at the 40’ mark anyway.
To the OP your rear axle will not lift nearly as high as your front axle will due to the arch of the trailer frame. That may or may not be an issue but it’s something to think about. You can always run a over inflation system to get you some extra ground clearance but that may get bouncy.