Transporting sheep, I find, is easy. I don't need to use a special trailer. I don't need to call in a livestock hauler. I don't need to cram sheep into dog crates. Nor truss them up with duct tape or rope. No. I use a "cage" that I made especially for my truck.
After measuring the dimensions of my truck bed, I custom cut and bent cattle panels to fit the truck space. I wanted flexibility in using it, so I didn't weld the pieces together. I simply used snap hooks to attach the pieces. That way I can take the "cage" apart to store it. And using cattle panels is far lighter in weight than using lumber. I can easily toss this cage into the back of the truck all by myself.
The sheep themselves seem to respond to this set up just fine. They aren't panicked. They aren't trying to escape. I guess because they can see in all directions, they don't feel trapped. Just guessing.
Above is a picture of the snaps I use to hold the pieces together. They are easy to put on and take off, and they are secure enough to hold the sheep.