Nudude I think you cought the point. Details are very important ... like being nude among other peolpe who are not.
In the last years of our relation I hardly used caroline alone. I mostly had guests, often more than one. Whether they were masters or mistresses, we always avoided to be nude in front of her ... we exposed always just the parts of our bodies that needed to be exposed ... she was always stark naked and barefoot from the beginning to the end. Only if we brought her in some public place, like a coffee shop, she would be allowed some dress ... but just the bare minimum and shoes were often not included.
Sometimes, when the sexual use of her was the main dish, when we had her playing the whore for us, we could even disrobe, but this could happen towards the end of a meeting, in the first part, when she was to be humiliated and tortured, she would be always the only nude ... especially outdoors and even in winter (mild italian winter days).
The pissoire humiliatoins started among us but were soon extended to all my guests and Helen was one of those who appreciated caroline as a pissoire more than others.
One of the greatest humiliations was when she was used as pissoire in a row by 3 or 4 masters during a break in a torture session. She had to go to the bathroom, position herself properly in the shover and than call out loud "gentlemen the pissoire is ready for you".
With regards to other toilet services, we did not like scat games too much.
Still, for the humiliaton sake and as a part of her education, she had sometimes to orally clean cocks or dildos that came out dirty from her own anus.
Assreaming was a common job she performed on masters and mistresses.
A couple of times she served as toilet paper: a great arousing humiliation.
I must admit that ones you have experienced your ass licked clean by your slave you would never use toilet paper any longer ... and I have a flashback to that memory almost every time I go to toilet....
As I said we did not push very much in that direction .... just a note: most female doms I met were much more interested in such kind of humiliations than the male doms (who preferred torturing).
I also like you fantasy about the old stable very much .... we had a similar one: the idea was to spend a few days in an old farmhouse (many are on rent in my area), with barns, stables and so on. Let's say a few doms and mistresses and 2 female slaves. During the day one slave would be "used" while the other would be kept in a toilet: nude, hands secured behind her back, collar and chain just long enough for her to reach any part of the small cubicle.
Here she would serve any guest and assist him or her in any way required.
She could be fucked, give blow jobs, lick the mistress pussy, but also receive everybody's piss, be used as toilet paper and take care of the cleaning of the place. She would have a bucket to flush the toliet ( we always immagined one of these toilets without seat, called the turkish toilets) and just her tongue to brush everything clean.
A horse whip, needles and painful tit clamps would be available outside the toilet for the masters and mistresses who may wish to amuse themselves with the toilet servant besides doing their things. There would be also some toilet tissues available: only to check if the slave did a good job ... if the paper would not remain clean, the angry dom would make a proper use of the whip and teach the lazy dog how to do better..
We never realized this fantasy even if in one occasion we had caroline cleaning a toilet room and vase with her tongue and also doing the inside of the vase in the same way, with the difficulties that you discovered and quoted in your message.
The age aspect you quoted is also very true. Helen and her husband were about 15 years older than the slave, and used her as a real pain-pet.
But it has beeen very interesting also to have caroline used, humiliated and tortured by both men and women much jounger than she was.