On vehicles equipped with automatic level control, the rear of the vehicle is automatically kept level as you load or unload your vehicle. However, you should still not exceed the GVWR or the GAWR. See Loading the Vehicle .
You may hear the compressor operating when you load or unload your vehicle, and periodically as the system self-adjusts. This is normal. The compressor should operate for brief periods of time. If the sound continues for an extended period of time, your vehicle needs service.
Using heavier suspension components to get added durability might not change your weight ratings. Ask your dealer to help you load your vehicle the right way.