DSteiner51 there seems to be a general trend with pickup rear springs to have a much softer early loading of the springs which creates two situations. 1. The rear sits very high when not loaded. 2. The spring pack compresses a longer distance before more load carrying capability comes into play!
Why? They have done this to improve light load driving comfort!
My old 2001.5 Dodge with the camper option is a "brick truck", with over and under load extra leafs. 2600-2800 of pin weight only takes in down about 2". The only way to smooth out the empty ride is to deflate the rear tires to 42-44 pounds when empty.
Some of the newer trucks settle 4-6 inches. People look at the truck on the sales lot and think they will have to raise their trailer until they hook it up and find the sky high trail came way down.
We have snowbirded in Arizona for the last five winters and there are 250/2500's bringing in very large trailer each winter. Reading here I just do not know how they ever make it! One of the important issues is to not overload the rear TV tires.
The biggest issue I see repeatedly is rigs showing up with the trailer side and unside beat up by cheap tires that have failed. Some can not hardly use their trailer the first week until they can get someone to show up and repair gas lines, electrical wiring, TV coax etc.
Chris