Running an aluminum
boat for a living, I looked into such a system. I was strongly advised not to install such a system because when they do fail, they can cause an enormous amount of corrosion
to the hull
and other metal parts
Zinc anodes either work or they don't...in no way will they ever actively damage a hull or other metal parts.
Cathodic protection works by creating a voltage opposite to that of the voltage generated by two different metals in an electrolyte (the water
your boat sits in). Some people have used it successfully but I don't think is worth the risk...not when the zincs are already doing a good job.
The sensors that measure the voltage created by electrolysis
can and do fail...giving the cathodic system a false measurement, resulting in damage.
Call the manufacturer and see if they will put in writing that they will pay 100% of the damages if their system fails or actively damages the metal. I think we already know the answer.