Ferengi physiology
I do realize that the concept of Oo-mox is a way to show sex on tv without showing it, because it's innocent by human standards. But I kept wondering, if Oo-mox is a way to reach climax for the whole species and not just some individuals with an ear fetish/hypersensitivity, then wouldn't it make sense, for this to be their primary sexual organs ? Or for them at least to be close by, somewhere in the head ? Then I wondered, if they reproduce (somehow) through their ears, why would they need genitals between their legs, if offspring came out a different way ? Ok, so what about urinating. Enter a documentary about platypuses and their urine glands. If OUR OWN planet managed to produce something this freaky as the platypus, no end to the possibilities on other planets. So urine glands it is. The glands should have been no trouble for early Ferengi, seeing that the rain was omnipresent and thus kept washing off anything left on the skin. Would also explain why many Ferengi have very high waisted pants, for extra protection of the glands and or padding to prevent leaking accidents. Also added a couple of mammary glands because at some point young Ferengi are just too big to be kept in the ear pouch.
Which brings me to size. The ears of male Ferengi are bigger than females, which enables them to keep a Ferengi baby in there longer, keeping them safer longer. With the female "only" providing the other half of the sexual secretions during conception and later on a foetus to wander over to the males head, this would also go on to explain why male Ferengi consider females so inferior.
If female Ferengi would also be like kangaroos or deer in that they had an extra amount of already developed embryos in their bodies, this would explain the restriction on female Ferengi. This would also give them some leverage during negotiations for the renewal of the marriage contract.
The secretion exchange doesn't happen everytime, especially when considering the embryo storing ability, but during a mating season. This doesn't stop Ferengi from physical intercourse and since no secretions have to be produced outside of mating season, virtually endless climaxes can be reached in a row.
Which again would explain why females have to be stored away, ensuring that Ferengi civilization doesn't break down from everyone oo-moxing all the time.
Changeling physiology
I struggled in the beginning how arousal and climax would work for a gelatinous life form until I made the decision for my headcanon that they can become aroused, but don't have a climax. I figured, since they could experience a range of emotions, it would be happiness and arousal as well, the latter being (a version of) the first. So in my headcanon, since Changelings can shift their very mass with their mind and mind and body are very interconnected, Odo's level of happiness rises when experiencing pleasurable moments, be they sexual or non-sexual in nature, until hitting a point where his cells start literally buzzing with joy (the sound Quark hears). He then keeps or even deepens this state of happiness for a while. For a human this could be compared to drug use. Or chocolate. Quark is Odo's chocolate.
Bringing my Ferengi and Changeling headcanons together creates this version of their relationship in which they can virtually keep making love until Quark has to take care of bodily needs. Even outside the bedroom, their mirroring sounds, purring and buzzing, creates a lovely symmetry and way to let the other hear their feelings.