The way it's packed in there is you have the tracks on the bottom and top and everything is sandwiched between them. From the bottom of the lower track to the ground I would say maybe 4 inches or so. Sorry the picture kinda *****. The crate only touches the ground in 2 places, which is in the front and back. The tracks are bolted to rectangular mild steel in 2 places per side. I might be able to go to where I have them stored to grab you some better pictures if you would like them.
How are you going to be tacking them off the trailer? With a forklift? With the forklift put the forks into the bottom part, and put the forks as far in as you can until the tips are at the end of the ply that protects the track. Then lift a little, and then tilt the forks all the way back and lift until just the very front of the crate is off the ground and go straight back. After that bring it as close to the ground as you can to move it around. It's actually really easy once you have done it once. It happened to be the first time I operated a fork lift when I got my lifts
EDIT: If you look where I circled in red, that's where the forks go, and that part is what's on the ground on both ends. Only contact points