OK - first you must realize that the entire setup on the 2019 Power Wagon is not anything like the standard Ram pickup. It has long travel suspension and is set up for off-road travel. Because of this - on pavement it rides like butter. On gravel/washboard road the ride is fantastic. Idea being - keep the rubber on the road. This is what the suspension is set up to do and it does it well.
The entire underbody( wheel wells and all - except the drive shafts) is sprayed twice with Line-X bedliner product. Same for the bed.
However - because of this very compliant suspension the Taco Wagon is rated to carry only 1800 pounds. This may be a negative factor for some. I bought the PW for fun. I DO ABSOLUTELY NO WORK with it at all. It is purely a vehicle for pleasure.
I have no answer for the ram box question. The tires are Goodyear Wrangler Duratrac - load range E. I run the tires at 65 psi - Owners Manual recommendations. They run quiet on the asphalt.
The last item. The PW has a lot of features I consider unnecessary. Heated/cooled drivers seat - sun roof - six way drivers seat - full leather interior - and a whole lot of features on the digital dash. I could either take the unit they had on the floor OR wait, forever, for a special order Power Wagon.