Here's a look through of the back of the cover. Clearance is the same on both sides, and basically the same toward the front of the cover (trailer). And I installed it using the instructions from Fantastic Fan.
After you lower the top, you can pull the cover off in seconds. Just remove the hairpin cotter pins and washers from the four clevis pins that the cover is mounted to at four locations. Then lift the cover straight up and off.
Here's the instructions for installing on a clamp mount fan mount. So if you remove the cover, you can see if they installed the screws at the four proper locations.