The good news is that all that paranoia was for nothing. Not a single leak. I walked, jumped, bent, lunged, straddled, lifted, squatted, pushed, and did countless other unusual movements. Halfway through the day, I successfully emptied my Lunette in the porta-potty. Lemme tell ya, I was extra careful not to lose my grip on it in there! And it continued to perform flawlessly throughout the day.
Doing that job on my "worst" day proved that my Lunette is capable of handling ANYTHING. (Except whatever position I slept in the night before. Hmmmmmmm.....)