your a brave man coming on rv.net and show how you increased your 1/2 ton any brand trucks rear suspension capability to better control your load. However without any actual scaled rear axle weights I doubt your overloaded with that small single axle TT and two lightweight dirt bikes. GVWR doesn't carry the load in the bed but the trucks RAWR numbers do. Looks like a good rear suspension upgrade.
I added Sumo Springs to the rear suspension on the wifes 1500 chevy crew cab 4wd. Even with a 1140 lb hitch load the truck is still 400 lbs under its 4000 RAWR.
Maybe you can get a mod to size your pictures to the proper scale where we can see what ya got.