Ron, do you have access to keel bolts? Is your keel external or internal? An external keel makes a good ground plane. An internal one, although not in direct contact with water is also good. I am wary of sintered bronze plates - despite their advertising they are electrically no bigger that any flat plate.

I wouldn't get too elaborate about tying in the water tanks and toe rail until you have tested an SSB with the ballast tied in - it may be all you need.

Last year during my major rebuild I replaced my copper and went only to the keel bolts (external lead keel). It works as well as the original grounding system dating back to when the boat was built. The original system had bronze screen under the water tanks and also tied into the prop strut, engine block, etc. I have a Sea 1612C antenna tuner.

PS. I'm sure you meant an SGC 230. although it has been commented that the SGC is a clone of the SEA 1612 tuner.