Im thinking of buying one for my.2005 crewcab longbox gmc k3500 duri duelly....since it rides like a dump truck..im leaning towards a all steel one for the extra weight..im thinking a 8.5'wide by 11' long.to fit 2 long tracks of course..and also for towing the usual 5th wheel and bumper pull trailers..who has them..and how do you like them.give me your likes and dislikes...at the least im going 9' long.thanx in advance..chris