Mounting a coil in a small deck is challenging. Everyone probably does it the way I do. I leave it on my coil mandrel and use that for a handle while I lay it between the posts with the leads on the bottom and facing out to the sides. I wrap one and tighten it, then wrap the other and screw it down. That's much easier than doing it free hand.
If it's not centered after tightening I just put my thumb on the coil and rotate the mandrel to "wind it" toward one side or the other and use the mandrel to align it at 90 degrees to the posts.
If it's not centered after tightening I just put my thumb on the coil and rotate the mandrel to "wind it" toward one side or the other and use the mandrel to align it at 90 degrees to the posts.