To clarify, in Washington state, the bike does not have to be present, nor does it need to have ever been titled in Washington state. Two days ago I walked into the DMV in downtown Seattle with an Alaskan title for a bike (never titled here), and a bill of sale, nothing else. With these two documents, my California ID, and a Seattle address (that they never verified in any way), I paid an extra $50 for a quick title and left in 20 minutes with a new title in my name, registration, and license plates. No hassle, they didn't ask anything or care that the bike wasn't present, etc. This is the second time I've done this, same both times. This is the main DMV office in downtown Seattle as well, not even a podunk office in the middle of nowhere. The official stated position is that if you do it in person, those are the only two docs you need. It is a bit trickier if you do it by mail, as you will need to provide proof of residency, but not in person.
Hope this helps someone!