I hope it is working out for you.
I would be very hesitant to add any weight or bulk to the prongs of the arrow rest. It could alter how it functions and/or the arrow flight.
As for using felt. Sometimes it sticks and other times or brands don't stick.
I've been using a piece of Gorilla tape, that I cut to fit the inside track, where the arrow rests.
I've had no issues and it seems to wear good too.