Luckily, I am retired so I can dress 'comfortable' & still conceal very well (we aren't allowed any leeway on printing, here in Texas).
I learned in the army, many years ago, that a t-shirt or undershirt does not mean 'hotter' in hot weather, in fact it's actually cooler if 100% cotton. I also found out that untucked shirts do not have to be the "hawaiian" flavor. The 'loose fitting' part helps with the heat & much more comfortable, to me, than the snugger fitting type. Plain old khakis or jeans are plenty comfortable & also cooler (I refuse to provoke ridicule from people by wearing shorts
The real ease of concealment comes not only from the size/weight of the pistol, but from the gear it's carried in. A proper holster & maybe more important, a proper belt are essential. Just my .02 worth.