Trailer weight distribution demonstration

A month ago, I was moving a hydraulic man lift from my house to my hangar to install remote radio switches for aircraft engine heaters. I made some forks for my tractor to pick up and move the lift as it weighs over 500 lbs. the tractor w/backhoe is 3,700 lbs. I backed the tractor onto my tandem flatbed and backed it up until the tilt bed went level then a bit more to get about 10% on the tongue. Then I set the front loader down with the man lift over the back of the trailer about 2 feet.

I didn't consider that putting the load down transferred the weight off the tractor's front wheels, which were maybe 4 feet forward, back past the rear of the trailer. I had already secured the tilt bed and didn't notice the unloading of the trailer tongue. Really dumb.

On the road, I didn't have far to go, less than 10 miles. It felt a bit squirrely, light at the back, and I realized my mistake. However, I figured if I went slow it'd be okay. Then, at about 40 mph, suddenly all heck broke loose! The trailer was yanking my truck back and forth light a dog shaking a rabbit. I slowed down slowly and fortunately no damage - - it was an "adult diaper" moment though!