Any trailer grossing roughly 5 tons cause the back of the truck to sit down. I had Lance modding diamond c tilt deck with nothing but attachments on the rack about 4 attachmentsand it squatted the truck right down.
Viewing post in 2020 Ford Super-Duty Limited (FS25) comments
yes I'm aware of the issues around towing with goosenecks, as you can see from the comments. It's a bit more then an issue with the truck. sadly the game physics don't take kindly to dynamic suspension and gooseneck attachments, I'm working on solving the issue. I'd love to see a screengrab of what your towing and how your balancing your load on the trailer? helps me to improve in future updates.