You live in Fla. and heat and humidity is the issue. Being that an IWB holster offers the best concealment options under a lightweight t-shirt a steel framed weapon is going to have a rust problem, even SS. I know that there are finishes and coatings that help, I have a 3.5 inch 1911 that has a ceramic finish and is supposed to hold up under a 1000 hr salt spray. I carried IWB for a while and in hot weather I felt that I had to peel it off my skin, very uncomfortable. I finally settled on a Kahr CW9 mated to a Beltman made IWB holster with a sweatshield. I wear a lightweight undershirt, kinda like the muscle builder shirt, under a light colored untucked t-shirt. The frame of the weapon comes into contact with the undershirt and not bare skin. I have carried this combo since mid May and we have had some high temp (99+) and 95-100% humidity days.
BTW I am not advocating Kahrs necessarily, any polymer framed auto will work fine. However keep an eye on the grip size.