We have had any number of big, water-loving, floppy-earred dogs over the years and battled the ear infection thing with each and every one of them. Eventually we got smart and we too found that the remedy for a yeast infection is great.
You can even save some $ by getting WalMart's Equate brand which has the very same active medication of the brand-names. That, and regular cleaning with the alcohol/vinegar wipes did the trick and we have had very few infections to treat over the last several years. We found the small, flat make-up pads to be perfect for this, using several for each ear until the wipe would come out clean.