If the previous owners were diligent about draining the tank between uses it may not be too bad. Electrolysis will only occur if there is water in the water heater's tank. No water - no electrolysis, and draining the tank will make your anode last virtually forever...well OK, at least several years anyway. As a rule I always pull my anode out between trips and set it aside and let the tank drain out. Without water to act as an "electrolyte" there is no path for stray galvanic current to flow so no damage occurs. If you do decide to replace the Hot Rod with a sacrificial anode, (which would be a good idea,) You really don't have much of a problem because you'll be strictly on propane. I would recommend the magnesium one over the aluminum one. I never liked the thought of having dissolved aluminum in my water, and there have been several medical studies done which at least partially blame leached aluminum (including aluminum from cooking pots) for early Alzheimer's onset. That's just my take on it, but health concerns aside, the magnesium one will also last longer, and they are the same price. FWIW, I don't use Teflon pans either, but I digress...
Edited by Euphoria, 14 September 2014 - 12:35 PM.