This plan builds a Super Duty Carhauler that can handle two 3500#, 6000# or 7000# axles.  Included are steps for the optional, angle rail, spare tire mount, triple tongue, electric brakes & slide-out wheel ramps.  Plans is adaptable for different widths & length trailers.  Trailer pictured is a 6' 10" X 20'. 

Sample paragraph

Step 3. Cut two pieces of 4" channel approx. 4" longer then the width of the trailer frame---or approx. 86".   Now clamp one of the pieces of 4" channel on the rear of the frame with the "C" facing the front leaving approx. 2" sticking out from each side & weld into place.   Then place the second 4" piece of channel approx. 15" (outside measurement) in front of the other but with the "C" facing the rear, measure for squareness and weld into place.  This will become your ramp tray. (Do not weld on the 2" outside part as you will be placing a 2" strap there later).