For the first - any dealer will sell you anything and will load it on your vehicle once you sign a release.
Look like HD loaded this car, what is real incident.
Than cargo capacity doesn't really apply to TC as you have very limited control of weight distribution and almost whole TC weight goes on rear axle.
That should be your starting point.
Coming to vehicle choice, sometimes it is not a choice. I am window shopping for new dually. Present super cab having 14 foot wheel base can get annoying on multiple-point turns, while all new duallies come with crew cab only and 172" wheel base. It will be fun to make U-turns with big camper on the back.
