I worked at a mold shop many years ago and they had magnets to load VERY heavy parts onto the mills and such. I remember being so nervous the first time I had to do it, but quickly gained confidence. At first, I couldn't believe the magnet would hold the part, I though for sure they were crazy.
And build a gantry that slides onto your towmotor forks and exends 5' past the tip of the fork with a hook for chains or straps to attach to hoist magnets. They will pay for themselves as soon as someone doesn't get hurt trying to muscle around a 600lb plate of material.
My material supplier uses a clamp that is basically bolted to the center edge of the plate and they just lay it on it's edge and tip it down to load 4' X 10' plates up to 1/2" thick on thier sheer. Problem with that is it leaves marks in the material.
Magnetic Hoist's: http://www.mcmaster.com/#catalog/114/1444