I put mine right on the underbelly material. Why cut it. Mine had self tapping screws holding it in and I was able to use a couple of those to put my brackets on. If they can put a screw through it, so can I. I put on two per jack so I have them at 90 degrees to each other. that way there is no front/back or left/right movement.
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2016 F 350 FX4 4WD,Lariat, 6.7 Diesel
41' 2018 Sandpiper 369 SAQB
Lovely wife and three children