I've had a couple sets of ski mounted scratchers.
1st set was on my 04 edge, they were mounted with a longer spindle bolt, worked very well untill my Girlfriend rode the sled. Reverse kills them quick.
2nd set was on my 14 cat. These bolted through the plastic ski. Ski deformed quickly so the scratcher was really useless. Just flopping around.
Make sure to mount it with the spindle bolt.
Mountain Cat