Some rough calculations on Number 2 production on Gardner Island from 1800's to present day attached, strictly a potential turd census for the island without consideration to particular toilet habits or facilities.
If the artifact does turn out to have Earhart provenance then it is one magic dookie amongst the other half million that didn't make the grade
LMAO/ROFL/LOL!!!
Yer killin' me... and excellent postulation / arguable research (yes, it "must have been so", hard to argue against.
Now that's one big pile of...
Wait, you didn't factor in the possibility of Earhart possibly having dysentery, etc. as you seem to have assumed healthy stools and regular daily movements like British Army clockwork here... not that less than firm product might survive so well, of course...
How to cut this one? Not sure, but for sure we still need to chase it - who wouldn't want the poop on Earhart having gone there, not that we can say where no man (or woman) went before?
Butt if it comes down to one magic turd and a slogan like "Earhart ____ed here" (reader's choice), I'll take it!

Never let it be said that TIGHAR doesn't have a sense of humor, even when rolling her sleeves up to seriously roll this kind of evidence around. It surely cannot be said that she's afraid of getting a little on her hands either.