Made some of those a few times. Best advice I can give you is to connect your pallets in THREES.
Basically, you screw 3 of them together to make the corner of a box shape. The reason for this set up is that no matter which way it flips once on the bottom, it will always have at least two sides standing up or it will sit like a pyramid. Either way, you get a solid 3-4' structure off the bottom.