Two observations.

In 2001 I took my Skymaster from Miami to Boise, ID. Each of our legs was 6 hours (one in the morning and one in the afternoon). I was 57 then (read: no spring chicken) and it was OK. I didn't need a bottle or anything, just limited my consumption of liquids.

Nick Bailey's Skymaster in the Virgin Islands has a nifty device which discharges your liquid waste out of a tube on the belly of the aircraft.

Ernie