You could easily learn to express the glands yourself. This would only need be done about once every month. I know it's a revolting procedure for the modern cultured mind, but it is very easy and just takes a few minutes. Most vets would consider removal of the glands as a last resort since it involves some semi-serious cutting, anathesia,etc.
You might want to Google up "raw diet"... some friends have gone to this diet for their dog and have eliminated (no pun intended) all problems with their dogs smelly rear end. In lieu of a total raw diet you may wish to try about a tabelspoon full of an unsweetened fiber cereal on the dogs food once a day. Best of luck!