Right on, Darryl. Take time and get the RH level right and (hopefully) somewhat consistent. Here in NE, I have a relatively consistent, humidified 45% - 50% RH in winter, but honestly in summer I get between 50% and 75% dpending on the weather. Other than a little belly, I've never had a problem with too much humidity. Where you are, the problem will be constant aridness.
in case humidifiers are essentially all good, but you don't need them if your room is properly humidified, Darryl. Get a hygrometer and, say, put it on top of your cases so you can see, ballpark, where you are. Your guitars cracked because (likely) you were well below the suggested 50%RH for an extended period of time.
But, anyway, dampits are great if you can't get the room level high enough. You'll probably find them dried out every week, just soak 'em in water and pinch/squeeze them so they're moist, not wet, when you put 'em in a soundhole or case. That said, a sponge in a perforated soap box in your case works equally well. Again, damp, not wet.
Best wishes.