I hope your doggies are doing better with their Demodex. A couple comments:
Ivermectin is an anti-parasite med given to livestock. It is also marketed in a smaller dose than would be given for mange as a heartworm preventative. Some dogs have trouble with it (ex: diarrhea), but others do just fine. Tae was on it for 2 mos this summer and had no issues whatsoever and recovered from mange beautifully.
The dips can be toxic to both dogs and humans. I did a lot of research on them this summer, both on BW and other websites. I was concerned my vet would want to dip Tae if her mange did not get better on its own. A dog that's dipped should not sleep in the bed with its owners and I believe should stay away from pregnant women. When dipping a dog, the dipper should wear protective clothing. While the dipper might not see any ill effects at that time, there could be long-term effects from repeated exposure. What's more, one of the side effects of the dips is the dog is woozy the day or several days afterwards. The wooziness is not due to being at the vet/stress, it is caused by the dip.
Goodwinol doesn't really help too much. My vet opted not to sell it to me b/c he felt it wouldn't really help. I did some research on this, too, and prevailing opinion is it doesn't do much for the dog.
My vet did not mention boosting the immune system. I learned the value of that on BW through reading old posts and corresponding via PM with Julie, one of the moderators. My vet did tell me, though, that most dogs are able to fight mange off without medication and it's best to wait until there are 7 "spots" before giving any treatment--at least this is his preference. When Tae continued to get hairless places, we started her on ivermectin.
Tae's hair came back in all spots but one. She has one spot where it is still evident to me that there was hair loss. No one else would notice, unless I point it out.