What exact "backing" is it that you are seeking? A note from your Mother will mean just as much as an FRT entry to any cop stupid enough to insist that the clearly-marked WK-180 is indeed an AR15. At that point, all you can do is comply with lawful commands from the ignorant officer, until such time as common sense comes to rule the situation. Aside from well-intentioned but willfully ignorant peace officers, your WK-180 sojourns in the woods ought to go completely unmolested.