Hi
There is much confusion and old wifes tales etc re ssb grounding.
Dynaplates are not much cop, period.

Copper strip is 'ok' and I am sure the manufacturers make lots of money from it.

YES, you can get an excellent ground by connecting to the keel.. no worries.
I use a single bronze through hull for the ground.. with a 23 foot whip antenna. superb..
If you want to add more metal, then you dont need copper plate or strip, use 6 mm cable, connect each item VIA a 0.1 uF disc ceramic capacitor to produce an RF path and block and dc hence no worries from galvanic interaction.

I service and repair SSB and radio equipment, including new installations and problem solving old ones.

A heck of a lot of ssb noise issues are simply land noise (No worries at sea !), battery chargers, fridges and other euipment. If you can get hold of an old RDF its a great tool, I use one to detect RF interference. works a treat..
Also, use a good quality atu.. the SGC SG230 is the mutts nuts.
Have fun, and gud dx.
Joe
G4XRZ