I was making soap in El Salvador for at least 2 yrs, a very humid country. I would make my soap with a 5% SF, like yours, no more than 15% coconut 76°F, anywhere from 30 to 50% olive oil, BUT I'd use a brine, meaning at least 6% sea salt content in my water which I'd use to dilute my lye. That will increase the longevity of the bar you're looking for that's good in a humid environment.
To counteract the bubble-killing properties of the salt, I'd add some sort of sugar: either just plain sugar, or frozen fruit puree, honey, a bit of frozen fruit juice, all of which increase not just lather but actual bubbles that folks like.
My family, and extended family, learned to love my soaps even though at first they turned their noses up because they didn't smell as pretty as the store-bought ones. When they used up their first bar, they realized just how much nicer their skin felt, and that if they kept their soap away from their dripping shower heads and on their own little pads I gave them, it lasted a whole month.
Also, I don't give them bars of soap before curing them for at LEAST 2 months. Especially because it's a humid environment. They'll sweat a bunch at first. DON'T WIPE IT OFF. It's glycerine drops asks it'll be reabsorbed by the bars. Just keep them lightly covered with some plastic, like what schoolkids use to cover their schoolbooks, to keep the dust and bugs away.
The only other suggestion for achieving a long-lasting bar is a good long cure. The longer a soap bar sits, the longer and milder it becomes. Other soapers with more experience and knowledge will be better at explaining why. My mind is right now a bit shredded with lack of sleep, and some pain. But I'm making soap as well as bread to distract myself, so I'm helping as I can, to distract myself too.
Right now I've got my Nanny in El Salvador using the very last of her lavender lard heavy soaps I made for her in 2021! She leaves hers on the top of the wall of her shower, well away from any possible water splashers, like her granddaughters, or her mom and aunt who live with her, and she's told me they last her better than 6 weeks, or 2 months, even though she takes a shower every day, even if when she's sick as a dog.
I made her 3kg worth of oils, which came out to 4.3kg worth of soap. I did give away about a kg, maybe a bit more, to her chagrin, but I said don't be selfish
. So, about 7lbs of soap have lasted about 21 months (I was there in July of 2021 making it).
Hopefully I'll have enough time & $ to go make some more this yr.
I hope this helps you, and anyone else making soap in humid areas. It's not impossible, all it takes is a bit of strategy!