I would also suggest getting to a scale. Not sure how it works in your state but I found in the state of NH, the DOT weigh stations on the highway always have the scales turned on. If the station is empty and not manned, I just roll in stop on the scale and read the numbers posted on the LED display. Don't even need to get out of the truck.
That being said, I just pulled for the first time in my 2021 ecodiesel, limited crew cab 6'4" bed and I was very impressed. I was definitely overloaded. The bed was full of gear, 4 rims and tires and lots of tools. I hooked up my boat trailer, it's all of 10k lbs if not more. The air suspension handled it perfectly, no sag or squat. Then I cranked in the Anderson WDH, just to be on safe side. I never used a WDH before, always pulled with my Cummins powered 2500 and didn't feel the need. Anyway the truck and trailer made the trip with no issues. I was half expecting the air suspension to have problems but none to be found.
Very impressed with this 1500 ecodiesel.