Well, ends up I bought a '01 F550. Now I need to get a gooseneck trailer.  I want to get 12k axles and electric over hydraulic brakes. 

Any suggestions for trailer setup? I am thinking either a 25 and 5 or a 30 and 5 length trailer to be able to haul a 1X55 tractor and a three, four or five bottom semi mounted plow. At some point the plow would get too wide to fit on the trailer.