I can carry my Kahr CW9 in a holster under a polo shirt. During the winter, I wear a coat with a larger gun under it.
Being from Texas its near impossible to conceal carry your weapon. Its just too damn hot to wear thick or oversize shirts.
I was talking to a crane operator while at a job and we were bs'ing when he brought up the concealed weapon topic. He said if you see a middle aged white dude with baggy shirt its best not to mess with them because you probably will get shot dead. LOL he is right.
During the winter, I wear a coat with a larger gun under it.
I carry a Glock 30, all year around without any concealable problems. With the right IWB holster, you can comfortably hide a full sized 45 while wearing cargo shorts, tank top and flip flops. All you gotta do is carry it at the 4:30 position (between your rear right pocket and right side pocket.
No need for single stack guns, downsized guns or guns with grip lengths so short you need extended mags or grip extensions to shoot comfortably.
I prefer the Glock over the 1911 because it holds more rounds, weighs less and is a much faster shooting platform.