Wow! So sad for your misfortune :(. Glad you and your family were not hurt!
I can relate some to your situation. I know the feeling of sitting on the side of the highway, watching your truck burn down, and not being able to do anything about it. Such a helpless and hopeless feeling.
I lost my F350 to a fire last summer, caught fire while driving on the highway. Fortunately, I only lost the truck (I was pulling a boat at the time). Fire department got there in time to save most everything rearward of the cab, and the boat. Truck was a total loss. It was a diesel. The fire did not start in the fuel system, it was electrical. Mine was a much older truck, '97, so likely nothing related to what caused your fire.
I hope you have a good insurance carrier. I have State Farm. They took care of everything and paid me off quite handsomely. I'm very happy with State Farm.
Like others have said, make a list of everything you were carrying, with approximate costs for each item. The costs really add up quick (especially with a trailer you were living in, I would imagine).