(3) A sport pilot must carry his or her logbook or other evidence of required authorized instructor endorsements on all flights.
So does anyone carry something other than your logbook? Any idea what the FAA would deem acceptable as "other evidence?" This is one of those questions that probably shouldn't be asked of the FAA, lest we not like the answer.
I'd prefer not to carry my actual logbook on flights, lest I screw up and leave it in some rental aircraft or spill my beer onto it during a rough landing. I'm thinking that a photocopy of the logbook endorsements would suffice.