@sprocket75,
The other issue you’ll encounter is the height of the damping trough. It will need to be raised some. My FFM is 5mm. I found a suitable spacer to go at the troughs’ pivot point. I found it easier to take the locking mechanism out of play as well. If you use a clamp you’ll just be re-connecting the lp to the bearing. YMMV.
Safe? Well as long as you don’t hit the record, all will be well.
With the mat in play, no part of the music suffered. I noticed the most how much cleaner/clearer/more musical the bass was. The bass is already a strong suit. A while back I tried my Stillpoints LP1 on top of the mat and that gave the music a greater foundation, increased solidity.