Steve,
We were outside Boise,ID and stopped in a rv park. In the registration, it was plain language that we would not be allowed to stay for more than 179 days. I ask why and was told it was a department of vehicles regulation. So , it just isn't Washington that has some wacky rules.
In the case of our park, yes it is perfectly legal to have two lots and move from one to the other at the end of a 180 stay. It is the sitting in one spot that the state and county regulate. Either the state or county would probably never say anything, but a lousy neighbor might. In my case, we let the county govern it and if they want to kick someone out, they can do it. Our binding site plan and conditional use permit says that the association has to have a method in place to "monitor" the 180 day limit. Nothing is said about enforcement.