Have a louvered tailgate with a wide 'U' notch.
Bought it when we went FT
One reason....ease of hooking/unhooking 5th wheel
Mileage...NO difference
Wind turbulence.....much less with the louvered tailgate
Full length mud flap.
YES....connected via receiver hitch
Kept front lower area of 5th wheel from getting hit with debris
BUT they was only AFTER I trimmed 2" off bottom of flap so when 5vr was hitched up the bottom of flap wasn't dragging on road surface
Stock length was too long and flipped 'stuff' up.
After the trimming.....no issues and it did protect front area of 5vr