Target Loading a trailer, and calculating adjustments

[Chamberpains]

I'll be making a copy of that for quick access in the truck. I've always hated using the center lights as the center point of a trailer. Sliding axles and tandems move the center point. So that light is useless.

Here's another question. How do you figure the center of gravity of a drive on piece of machinery or non crane loaded piece? That has always been a huge guessing game to me. I use measuring the center of lifting hooks if they are available. But do you have any tricks on non conventional pieces? Any crane operators that may have a trick or 2?