i'd try 5200 over silicone. i used drops of 5200 on my transom when running cables for transducers instead of screwing cable clamps into the transom. did it 20 years ago and its still there, holding the cable. bottom machine is long gone.
I agree I put a pair of 18 led (noncharging)on my old crestliner 5200 and shallow seft taping screws worked great for me , by the way these lights are great http://loomisled.com/
i'd try 5200 over silicone. i used drops of 5200 on my transom when running cables for transducers instead of screwing cable clamps into the transom. did it 20 years ago and its still there, holding the cable. bottom machine is long gone.