Other than really not wanting a second Washington State I don’t have strong feelings about what the proposed state should be called, but I do feel strongly that the common name* for it should be a maximum of two words, (or three only if they decide on District of Columbia). “State of Washington, Douglass Commonwealth” is much too long.
- it could include a seldom used, official “Common wealth of” appellation if necessary. Though these days “and Providence Plantations” is right out.