Interesting to see you show us a photo of such a thing Mark.
One thought I'd had (in previous years) was to buy or make a little mascot (say 2" or 50mm high) which I'd take around the country and shoot with my P&S (small sensor = wide DoF) at the wide angle/macro so that the background was sharp enough to see where 'we' had been.
I got as far as determining that if shooting it in sunshine, I didn't want it to be shiny in order to avoid specular reflections of the sun (or me) - these materials look quite suitable.
Not an original idea and I never got around to starting it as I didn't have the creative ability to design and build it.
Is this part of your plan?
Does it have a name?
"Antenna Ball" doesn't really roll off the tongue