See an ENT (ears-nose-throat) doctor before deciding on any gear fixes. There are two things I see wrong with your diagnoses. Your wife may not have a physiological problem with ear clearing at all, it could just be technique.
First you say your wife get's tropical ear infections, this tells me she gets water trapped in her outer ear canal. Next she has trouble equalizing, this tells me she can't push air through her Eustachian tubes, which is a middle ear problem. The Eustachian tubes are located right near your tonsils and leads up to your middle ear.
Having a narrow outer ear canal should not affect the ability to equalize. Having thin tubes does. It could all be just a technique problem with equalizing. Does she have any trouble popping her ears on a plane or when ascending a mountain? If not, then it's probably all technique.
Keep in mind there are 3 techniques to equalize the ears
In order of which is more forceful (harsh and possibly harmful) to which is less when equalizing your ears:
Valsalva Maneuver:
Plug your nose and exhale into your throat. Often incorrectly called blowing your nose. You're actually trying to inflate you throat and blow air into the Eustachian tubes located in your throat. Blowing your nose, people often constrict their throat, impeding ear equalization.
You can also blow too forcefully, harming or inflaming your ear and even go as far as to burst your ear drums from the inside out.
Frenzel Maneuver:
Hold air in your mouth, and in one fluid motion push your tongue onto the roof of your mouth, starting from tip then rolling to back. Very similar to what your tongue does when you swallow.
The idea is to use the tongue as a piston to shove air into the Eustachian tubes. Can be done hands free, but holding the nose may help.
Having independent control of soft palate and epiglottis makes this easier. Soft palate closes the airway between your nose and throat, epiglottis closes between throat and lungs (holds your breath). Closing both off will allow the air to be directed into your tubes when you equalize, if one is open, the air won't go into the Eustachian tubes.
As such, when scuba diving, you should never hold your breath. So this has to be done in one fluid motion. It takes more technique, but is less forceful than the valsalva manuever. It can't be forced, so your ears will never become stressed or inflamed with this method.
Voluntary Tubal Opening/Beance Tubaire Volontaire:
This requires voluntary use of a less often used muscle in your throat. You basically use this muscle to pull open your Eustachian tubes and allow air to passively equalize from your mouth to your ears. When freediving you need to inflate your mouth. When scuba diving you just need to breath in and out normally. It is said that not all divers can anatomically pull this maneuver off, but I think it has more to do with mind/muscle control.
A cheaters way of doing this is to hitch your jaw forward and open and pretend a big yawn, without the usual big breath in and out; just use the muscles you normally use to yawn.
More on Ear Equalization:
Ear clearing - Wikipedia, the free encyclopedia
Also, to prevent the outer ear infection from trapped water, you can use swimmer's ear drops. A home remedy is a mixture of isopropyl alcohol (rubbing alcohol), distilled white vinegar, and distilled water.
The alcohol helps the water to evaporate, the vinegar is antibacterial, and the water dilutes it so it doesn't burn like crazy when it's in there. Just use a medicine dropper and add a few drops into your ear after a swim. Let is sit for a few seconds then tilt your head and let it drain out.
There are different ratios of mixes that people swear by; since I don't have this problem, I don't use it and can't recommend a ratio. I just use clean tap water; I'm lucky. You should always rinse out your ears IMO after an ocean swim.
