The two 80 gallon tanks: Do the tanks supply different fixtures? If no, are they plumbed in series or parallel? Are you heating water off peak only or on a water heater sub-metered program?
If you are just trying to have a quicker recovery you can get just one 80 to 120 gallon WH then change out the lower thermostat with another upper thermostat and then feed the new lower thermostat with a separate circuit. Now you will have the same heating rate as two WHs with “factory wiring”.