Glad this question was posted because I have concerns about which anode to choose, magnesium or aluminium.
Like NashTT I never had an anode rod in the past but my new trailer has a magnesium anode that looks like swiss cheese after a single season and I estimate is about 1/2 consumed.
Since we travel a lot, we probably average a dozen different RV parks (different water supplies)in a month and never know what water to expect.
A couple of you have answered that you use aluminium but I believe that magnesium gives more protection?