Sounds like too much tongue weight. Assuming you aren't exceeding your vehicle's tow capacity, the tongue weight should be about 10% of the loaded trailer weigh

Sounds like too much tongue weight. Assuming you aren't exceeding your vehicle's tow capacity, the tongue weight should be about 10% of the loaded trailer weight (check your owner's manual) which the suspension should be designed to handle and thus not tilt your vehicle under load. Or you may have a worn suspension...