Training Logistics

There is a small problem at the K residence and it is in the form of a wee Spaniel who likes to bark. I understand barking is a natural thing for dogs, but this is excessive barking. It is a problem.
Somehow, I have to find a way to get it under control In an attempt to figure out how to control the barking, I began thinking of ways to change the behaviours that are associated with the racket. Some of it I can't change, but some of it I can and so I am going to try. Try and hope that by changing some of it, the rest will follow or at least become more manageable.
Part of the reason why Hermione barks is because I can't see her or really hear her, moving around because she's so small. Unless, of course, she's vocalising. She's learned that if she squawks, squeaks, yips, barks Etc, I will hear her and come to figure out what she wants. It's gotten ridiculous. Two of the things she barks for is needing a drink of water and to go outside. Both of these behaviours have alternative noisy ways to let me know what she wants.
The water, for example, is solved by encouraging one of her natural behaviours. When she's thirsty and an empty bowl is around, she digs in it. I can handle this over barking. As for going out, I've started training targeting with her so that I can teach her to ring a bell to go out. I've always thought the bell ringing was a novel idea and thought it would be fun to train, but now it's moved from the realm of "fun and neat" to "necessary."
The only problem I'm having is managing a multi-dog home during training.
In the past, I have left the dogs not being trained in the living room and taken the one I am working with to a different location in the house. The ones in the living room get upset. They tap dance, whine, sometimes bark, whack the baby gate with paws. I'm really not sure what to do with them. This has been my biggest problem in training and honestly, it's sort of turned me off of training. I haven't done nearly as much as I should because of this problem.
I have signed up to be a part of a working dog forum and posed my question to the other forum members. I've only had one response so far and it was half unhelpful, a quarter scary and a quarter sort of helpful.
The person suggested that I kennel the other dogs, train in a completely separate location (not feasible when you can't drive), "teach the other dogs to chill the *f* out" (their words, not mine), or use muzzles/Ecollars.
I probably don't have to talk about my problems with muzzles or Ecollars. I'm not even sure what a muzzle would do for a dog who is hitting/jumping over a baby gate.
The chilling out part would be good-minus the F-but they didn't tell me how to teach that.
The other dogs are just excited because I'm off with other poochie, clicking like a mad woman and dispensing kibble. They all know what that click means.
So, what do I do?
I could train outside, but that is an incredibly distracting environment. That is not the place to start training a cue.
One solution I've come up with for now is training Hermione targeting while everyone's eating breakfast/supper. I've always fed her last and so this morning I used her breakfast to get her to start targeting. I'll do the same tonight at supper time. The other dogs were too invested in their meals to notice. I actually think locking them behind the baby gate causes even more of the excitement.
Has anyone trained four dogs at once?
I could use the time to work with Nala and Roscoe on sit/down stays and train the other two?
Oh dear...I am sure chaos will ensue. Then again, they have to listen to me when they are all together anyway: why not try it this way?
Everything I've read says that one on one training is the best and all dogs need the one on one attention. The breakfast/supper with Hermione could be her one on one training time. Nala gets one on one time when we go out and work. So, it would just be Otis I'd have to work with.
I guess I'm just going to have to get creative.