Alternatives for undershirts when CC

I live in a very hot climate and don’t want to be wearing a lot of layers. Any suggestions for undershirt alternatives? Someone had suggested a bandeau bra but I feel like that wouldn’t really work in the waist area but something like that I think can work but just not sure what it would be called. Or maybe something on the holster itself so it’s more comfortable and doesn’t require an undershirt.

Open to all suggestions. TIA!