Never put alcohol or peroxide in your ears. You can destroy the ducts that make the "ear wax" and if you have a perforation... You will not find that outcome pleasant. I suggest you get a script for Ofloxacin, been using that for years with great success. If you really want to keep the bat duky out, get some doc proplugs. Flush with the drops, install plugs and go. The plugs are "micro-vented". The plugs also act as a pressure buffer as well in shallow water, move up/down 6-8 feet without feeling the need to equalize.
I just got back from a week long dive trip with about 22 dives and zero problems. I have had perforations for over 40 years, in one or both ear drums large enough to vent air through them and can dive using my method keeping the water out of the middle ear. If all you are worried about is water contamination, that should work well for you. You can also get mastoid infections through your eyes (tear ducts) and nose as well, so you just might want to start an antibiotic regimen before and during your stay.
I'm going to offer council on cavern diving too.... as long as you can see daylight you're good to go.