For what it's worth, I've moved away from the baggy Hawaiian tee. Short of a black fanny back, nothing screams "I'm hiding a handgun" like cargo pants and an obnoxious print untucked shirt on an otherwise clean-cut dude.
Bonus points if you happen to be wearing one or more of the following with it:
1. Heavy tactical boots
2. A ballcap bearing the logo of the NRA, a gun manufacturer, a range, or a popular firearms website.
3. A clip knife in your pocket.
With a good kydex IWB, I've found I can hide a Glock 19 even with tapered athletic-fit shirts. I've all but given up on tucked carry and only drag out the belly band when I have no better choice. I've tried several tuckable holsters and they all were either unstable or exposed a curious-looking belt clip.
With my favorite Comp-Tac IWB, the metal slide of the Glock is fully protected from my skin. I've started to carry without an undershirt more often than not in Texas this summer. If I'm going to be out for a short while and mostly in air conditioning, it works fine. Come home, wipe off any sweat, and into the de-humidified safe it goes. I'll add the sleeveless undershirt if I'm going to be out longer.
