You can also use the two-part epoxy, the kind you need to knead together to form the compound. Put it under the top surface of the cliffy that will stick to the pf...and on the vertical piece of the cliffy that will stick to the inside of the hole. It should dry and adhere it to both surfaces. Maybe that will work instead of trying to get it to clip in place.
Other thing is to just message Cliff. His attitude is really good and should be a good source of help.