[Belmont Resident]

You are making a very simple job into a project.
Pick up a tube of marine caulking, drill and fit all of your pieces where they go. Drill the recommended size hole for the wire to come through the transom, this is usually done in the same area as the outdrive so it blends in. Use the marine caulking to fill all of the space and seal the hole in the transom then apply a small amount into the screw holes and onto the screws before putting them in.
Wipe up any extra caulking and you are done.
Your boat will not look like Swiss cheese unless you make a mistake, this is the way any boat that does not have through hull parts is done.
The biggest thing you want to avoid is leaving an avenue for water to penetrate and freeze. This is solved buy using the caulking to seal all holes.