One thing you may want to consider...truck length. When we bought our current TC, we had a F350 4x4 extended cab. The weight of the camper was a non issue. However the ride on that truck was a problem. There was an airflow issue between the camper and truck that set up an oscillation that drove us crazy. The high pitched whistle was nearly unbearable.
For another reason entirely, we decided to trade trucks an get a crew cab. Not only is there no noise issue, the ride is incredibly better. The difference of a few inches was remarkable.
As far as the 4x4...speaking from experience. ...the one time you need it, it will pay for itself. Ask me how I know.
Even tho we are no longer fulltiming, we use our 4x4 capability frequently, especially in winter.