@Gubbin ... Honestly?
I wasn't being satirical, so much as I was being merely inane..
I cleaned my van out, & that evening found i dinna a reservoir..
Having to pee into a tiny holed glass bottle in the dark was (as it has been before) an act requiring caution & a bit of bit of dexterity..
After finishing, I said "O Shit!!", & remembered I had a large OJ bottle, that I merely needed to finish, in order to provide for the next episode.
This, in turn, reminded me of when I accidentally stuck my dick into a jar of jalapeño juice (which is definitely *not* a good bottle, unless you get off on being branded, or shit like that..)
Had I been speaking of the best way to bag & dispose of actual crap, perhaps I would have sounded a bit *less* tongue in cheek, or a bit more as if I had my finger up my ass, but
@Odin 's suggestion of a laundry bottle is so utilitarian that it actually merits experimentation, and will in fact be put to the test.
Inane intentions or not, that bit of a score of practical reasoning was certainly worth the thread...