Look at your tires first and find out what ply they are and the load capacity. These are the things that will go first, especially if they are over 5 to 7 years old. (date is on the tire somewhere.) If you add up all the tires and come up with close to 4000 you need a bigger trailer and better tires.
My VX weighs almost the same front or rear axle. If you can center it over the tandem axle trailer it should level out. You don't mention how much stuff you have in the back of the truck. That will affect where the tongue of the trailer is too. Also if you have a drop hitch, try turning it over to make the trailer level (you will need to unbolt the hitch ball)