Dude you don't need a dehumidifier for 60% humidity unless your house is getting to that. If chameleons gaped because of humidity, they'd be gaping all night. only in the chameleon world is gaping even considered bad(it's probably not, no one seems to really know, but in other animals it's simply temperature regulation, including reptiles). If they were overheated they wouldn't sit there and gape. Most of us with panther have seen it too.
@Beman sorry but I just don't agree with you on this and I have yet to see any proof from people that this happens regularly, but I believe you, I just dont think it's a bad thing. All my chams acted differently when they were too hot. I've seen them gape when they're content in their basking spot. When overheated they move around in search of cooler areas. Some people do not have $200 to spend on a dehumidifier. If they did, then that's great, but I don't think it's needed and personally would not buy one in this case. Just saying this as a friend who respectfully disagrees, not trying to be a dick.
Not saying I'm certain I'm right either, but then again, nobody is. just my opinion and experience.