What about this section?
Section 803 – By-Laws
No person shall be entitled to use or wear any seal, emblem, badge, insignia, or uniform of the Veterans of Foreign Wars of the United States unless he is
a member in good standing or is authorized by National Headquarters.
I suppose if your Honor Guard uniforms, including headgear, are devoid of any mention, symbol, or emblem of the VFW there would be no problem.