Um, just for clarification, the reason campers use a pee bottle while camping is because it gets cold in the mountains and it's alot more convenient to roll to your side, unscrew cap, pee, replace cap, go to sleep, then unzip your bag, get up, go pee while freezing your butt off, then get back in, re-zip, and go to sleep.
I've done the regular old get up method while camping, and I'll take the pee bottle method in that scenario any day. Let's not even talk about serious altitudes where it's like -10 degrees and the windchill factor brings it down to like -30 or colder.