Concealing weapons & gear can be tricky.
I've seen sworn LE officers, PIs, armed EP(bodyguards), and armed citizens who "printed" or had those "tell-tale" signs.
Thick fabrics, dark colors, prints/designs, layers, etc all help conceal weapons.
A gun writer I recall wrote several years ago that clothing/garments are like an illusionist or magician.
You want to draw the eye or vision away from your loaded firearm & have it blend in seamlessly.
Im not into the HI or Thomas Magnum Aloha shirts. I also do not wear the Tommy Bahama style but it could work in the US southeast/Florida.
Some FL residents like the Cuban style casual shirts which are untucked but are still stylish. I think you have to be over 60 to pull that look off,
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I also do not own any "camp" shirts or Bowling team shirts even though those garments could help concealment. Im not a big Charlie Sheen fan,
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For general wear in hot climates or warm weather, Id go with the practical, simple safari or 5.11 type vest. The extra pockets can carry kit or back up stuff; white-light, cell phone, folder-knife, first aid or "blow out" kit, badge/ID/creds(if required), spare magazines or speed strips, passport/documents, etc.
In warmer areas you can get a vest in khaki, OD or a grey color.
ClydeFrog