On the older American Appliance heaters, the anode had a separate connection on the rear of the heater, plus they were originally equipped with a drain cock anyway. I realize it is probably easier to drain with the valve, but it's more important to have that anode in the tank. In the long term, it will be worth the extra time it may take to drain the heater between trips.
As a side note, I’ve seen some mis-information posted on online blogs recently and wish to clarify when to replace the anode. Suburban recommends replacing the anode annually or when the rod has about 25% of its original size left. Heavy travelers may need to replace the anode more than once per year, but typically, once per camping season usually suffices. If you are a full-timer or travel often, check the anode at six-month intervals and replace it when it’s 75% deteriorated.