RE: AMA numbers on aircraft
As noted, the VFW, Disable American Veterans, Paralyzed American Vets, and a bunch of other charities will inundate you with address labels if you ever send them a small donation. And you can put the label someplace in the wing saddle area.
Many times however, I just use a fine tip Sharpie and write AMA 15654 on the rear wing bolt hold-down block, or the bulkhead at the leading edge. I don't worry about somebody finding a fly-away, the type of planes I fly are not apt to end up in one piece if the radio locks up and they fly away anyway.
Sometimes I cut the numbers from Monokote and put them on the wing if I feel I need to enhance the looks of the plane.
I do think it is wise to follow the AMA rule here, rather than risk any challenge to your insurance in case of a problem.
Clair