I would not do a stent if it were my dog. I have not ever seen one live for longer than a year after that surgery. I am not saying it never happens. I just have not seen it happen. I had a foster who died this past Christmas...he had CT and it was severe. I spoke with three different vets and one was a board certified surgeon and not one of them recommended the surgery. They were frank with me about the low successes in this surgery.
The following site has detailed information about stents. I am not so sure about their numbers, though.
ACVS - Tracheal Collapse
This site also has information:
Small Animal Surgery Services UF|Veterinary Medical Center
I am sorry you are going through this. It is an awful condition and stressful on everyone.
Have you tried Lomotil? If not, ask your vet about it. It helped my pup and has helped others that I have told about it. It is an anti diarrheal, but for some reason does help with CT. If your vet has not heard of it's use, tell him it is in Kirk's Veterinary Therapy book!
I am sure you are aware that it is good to keep excess weight off of CT pups. Also, they need to be in a stress free environment and air conditioned. Heat and humidity exacerbate the symptoms.