I have had a few pups with CT and can tell you that I would never put one through that surgery! My most recent one was seen by two specialists and while the one said she could do it, when I pressed her she did admit it would probably only work for a time and that sadly, his prognosis was not great. The other specialist told me what I have read many times...those stents do not hold up.
One medication that I have used with success and know of others who also have is
Lomotil. I have mentioned this many times on YT but seems that people have not caught on to its use in these pups. The information and dosing can be found in Kirk's Veterinary Therapy a book that most vets use. I am sorry, but I am not sure which volume it is in, but your vet should be able to find it. Why it works...I am not sure of the exact reasoning. It is an anti diarrheal that has been around for a long, long time..it does have an opiate in it, so maybe that is why? Not sure...but it did help a foster I had for some time. He also was on steroids daily...and I had injections on hand for those times that he would really get out of control at night. They were a combo of Torbutrol and Ace Promazine. Very tiny injection and not difficult to give if your vet is willing to try it. That is used only when they get so bad that they cannot relax! It really does help.
You are doing a good job about keeping him out of the heat and humidity...that is really rough on them as is any weight gain.
I will say a prayer for him and for you. I really sympathize...it is heart breaking to see them suffer with this condition.
Feel free to PM me if you ever have any questions or just need to talk.