I just remembered from my first post that I also have the speed paddle installed too, so that is more holes in the transom than I remembered.  Is there a better hole filling procedure than my silicone and a screw procedure?  I thought a could do that and then cover the back of the mounting plate with silicone too?

Thanks again!

Use the 3M Marine 5200 sealant for the filler screws and you won't have to replace it occasionally like you will with regular silicone sealant.

What about using J-B Weld to fill the holes?

years ago I installed a transducer board and all I did was fill the screw holes with silicone,let it set up a bit then put 2 beads of silicone around the board and mounted it..