I had trouble finding specs on the Smith, but found the Rheem. The powered anode isn’t a solution here because of the location of the anodes and the geometry of the inside of the heater. A heater like this has four anodes inside the space where the exhaust gases vent. The heat will probably damage the powered anode or anodes.
Indeed, getting to the anodes to check them will probably be a lot of work unless the heater is side-plumbed.
For those who read this post: the Rheem heater is a 90-gallon, 715,000 Btu tank. Very expensive to be replacing every two years!
I’m thinking that you should consider replacing the water heater with a boiler and storage tank. The softened water will keep the boiler heat exchanger clean. Putting a powered anode in the storage tank is more feasible and there will be no flue gases to harm it. The powered anode would be a permanent replacement of the factory anode.
Hope that helps.