Delvin
How about this? Start a corporation in the nearest NFA friendly state of your choice.
That could be your answer. I have not done this but maybe someone here can guide you.
I know corporations can buy. I know you can arrange to store the weapon legally in a variety of ways OUT of the state of Washington, as I am doing this now. I live in Canada and my NFA collection has been in storage in bank safe deposit boxes, Class III dealers and in friends homes (in locked cases under my key control) and I have stored them in two different states.
What I am not sure about but feel fairly comfortable that it can be worked out is how the Form 4 is filled out for address with a corporation. Is a physical address required (I think yes) and if so can you get a physical address? Would a resident agent address for the corporation qualify ( I dunno )? Resident agents are usually a requirement.
I have heard others talk about dual residence, there you would need to qualify for residency in another NFA friendly state. This is another story.
Michael