Since I have worked as a groomer, I have come across a lot of ears lol.... bad ones and worse ones. Always the dogs with hanging ears are worse to deal with, they get infection easier than the ones with standing up ears. You may already have tried this. But if you really really neatly clean them out, with plenty of q-tips, one for every time you go down there, go pretty far down, use a good earcleaner, and really swab around both inner and outer ear. I find that with large dogs it is sometimes as easy to use papertowel and your finger, at least the first batch, then use q-tips for where you cant reach. When you are pretty certain it is clean, drop a little cleaner, or even the cleaner that has the protection against earmites. Rub it in and let sit for a couple of min. Then go down and clean again, this way you should be able to get everything up that is even far down. Now you got a clean ear. With long coat, I would put his hears up, pin them together over his head with some kind of hair clip. Just long enough for them to really dry out. The most common reason for infections are moist environment in the ear. When you know your ear is completely dry, or even inbetween cleanings, you can use an antiseptic ear powder, that will help the ear stay dry. Just make sure you dont mix the wet from cleaning with the powder that will make some kind of not so healthy "juck". I have adviced a lot of people with dogs that have problem ears to do this, and if they do it fairly regularly it helps quite a bit most of the times.
Good Luck
Marit