Sorry if this is a stupid suggestion........
Julie, you say Coco is ok coming into the field with you on a lead, could you not then perhaps use a long line and tie it around your waist?
This would mean that you would have control of her actions at all times but still have hands free for her and the alpaca's.
No, sadly that wouldn't work as she would be barking and lunging at the alpacas then

When I have taken her into the field, I have just walked her round the field not near to the alpacas and she is fine - when I do that I am giving her my full attention though. I need to be able to handle them and feed them etc plus doing stuff where it would be hard if I had an exciteable cocker attached to me!

Also, I am trying to get them used to me being around and handling them so I am not sure Coco would help their confidence just yet!
My ex groomer used a citronella collar on her dog Tyler. He used to go in a corner, shut his eyes and bark nonstop until it ran out and then run round barking with glee. 
Yep, I can see Coco doing that too

My neighbour was told though that you must never let the spray run out - that way the dog doesn't learn that they can empty it! I can see me having to buy citronella by the gallon

I have a Mekuti Calming Band, based on the TTellington Touch. Fixes in a figure of eight around the muzzle. It does work inasmuch as it makes her think when she is having a silly session, barking at me when I am in the outer garden and she settles and sits and watches, or sleeps, instead (still the occasional woof!).
Most of the time, if she really starts, I only have to wave the thing at her!
This sounds good - I might try one of those in conjunction with the ear plugs, clicker and treats

It would be good to have something to use when I do not have the time to turn every trip to the field into a training session
