Male planters dress code

Answer 1

The "planters" lived in tropical climates. Hence, dress of the evening was not normally a dinner jacket, but a slightly more comfortable dress; less jacket and tie.

In the modern day, this is considered to be a collared, short-sleeved shirt and dress trousers of a linen or superior fabric.

Shoes, not open footwear; commando is optional, depending on your profile and intention for the evening!

As an RAF officer in Singapore, 'Planters' was smart shoes, trousers, longsleeved shirt and tie.
See also:
shirt (short) sleeve order: short sleeves, no tie.
Red Sea rig: basically DJ without the jacket.