I'm 6'1" and 225 lbs and I'm partially handicapped, so it isn't muscle. I suffer from hyperhydrosis, meaning I sweat easily and I sweat a lot. I use Crossbreed SuperTucks almost exclusively. They keep all of the gun away from my skin except for the butt, but since I almost always carry a Glock, rust isn't an issue. I carry at 4 or 5 o'clock so my 'roll' isn't a problem. If I'm wearing very light clothing and I'm in conditions where I might get wet, I do have a SmartCarry holster for my Ruger SP101. The gun is stainless so I don't worry about rust, but the SmartCarry is difficult to draw from, so I don't revert to this situation very often. If I'm on my handicap mobility scooter, it's pretty much impossible to draw from a SmartCarry. Same for inside a vehicle, boat or anywhere else you're sitting down.
I order tall size shirts almost exclusively and I have to order them online because I can't find them locally. You don't expose the gun when you bend over or reach up high with a tall size shirt, and almost every place with tall size shirts also has big size shirts, or a combination of both. I've also discovered Hawaiian shirts. They're loose, made to be worn untucked, extremely comfortable and you can concealed a howitzer underneath them if you want to, especially if you get them one size larger. And since they're designed to be worn loosely, one size larger still looks natural. Going to Hawaii again in May so I may pick up some more. There's always a better selection there than there is online.