I live in SW Florida, and try to limit outdoor gigs as much as possible, and avoid outdoor summer gigs, but I still play maybe a dozen per year. I tried whining about it- it didn’t help.
I never tried any drops or products. I’d just keep wiping things down. More often, it’s the sweat from my arms and hands, that kills my strings. To help, I use a thick wrist band on my plucking wrist. Things still get very wet and sticky. Comes with the territory, as they say.
I really don’t have a solution. Ultimately, I try to plan my string changes for after those outdoor gigs.
As for strings, Dunlop Super Bright Nickel seem to maintain their snap during the gig. The feel is pretty normal, but the back of the neck is quite sticky. After, I feel like I need to change them. Some folks may boil or otherwise recondition. I just replace them.