During hot weather I mostly wear short sleeve button shirts from L.L. Bean. They are a fairly heavy cotton so even if it is really hot and sweaty weather the shirt doesn't become uncomfortable as would a polyester material shirt. Wearing these shirts untucked with jeans or shorts allows me to easily carry in an OWB holster, or a pocket holster, with nothing showing at all. And wearing an untucked shirt is a lot cooler than having it tucked in. Sometimes I just wear an untucked t-shirt with jeans and shorts, but when I do so I pocket carry exclusively.
FWIW, when I first started carrying concealed many years ago I was pretty obsessed with making sure I did not print or otherwise show that I was carrying a gun. It took me awhile to realize that people do not notice pretty much anything and that they will ignore even obvious printing of a firearm. Either they are so wrapped up in themselves or their cell phones that they don't see the printing, or they just assume it is something big in your pocket or whatever. What really convinced me of people's blindness was an occasion many years ago when I was at lunch with my wife at a restaurant and had to use the restroom. Somehow when I finished using the restroom, my untucked shirt ended up behind my holstered gun on my belt, rather than over it. I essentially was open carrying, something not legal in this state. I returned to my table, finished the meal, we left and walked out to the car, all with my gun fully exposed until just as we reached the car my wife said "Fix your shirt, your gun is showing". I must have walked past 30 to 40 people with the gun in this condition and no one said a word nor apparently called the police or anything else. I learned that I did not have to be so scrupulous about trying not to print.