Need some real curb weight help!

[Country Suburban 4x4]

Hey guys, my boss offered to trailer my old suburban out to Ohio for me so I can have it with me in college, and him and my dad put it on his trailer this afternoon, it fits, but is very heavy. So much in fact that it lifted the whole ass of my boss's truck almost 5 inches off the ground when they backed the Suburban off the trailer again. I have a GM Heritage Center PDF that says curb weight is 4991 lbs on my 1983 Suburban K2500 with the 350. I've heard the factory books can be misleading. Any help is appreciated as the truck is too heavy for the size/design of the trailer and it won't be making the 800 mile trip until we figure something else out
Here's the truck while loaded on trailer, real front heavy, the trailer jack is only about 2" off the ground.