Why would you need to drain the water heater three or four times a year? We traveled for years and only drained ours once per year and flushed out all the sediment at that time with a wand through the drain hole. We never drained it in between stops or campgrounds.
Our present trailer is 16 years old and has the original 10 gal Atwood gas/elec water heater which still works great. I see no need to drain several time a year unless you camp in areas that have horrible water in which case I would probably not be stopping there.:W
Barney