I have grown them for many decades and love them too.
I also travel a lot and in an area of Thailand where they have 12/12 sunlight/dark and a mild climate of a constant 70-80 degrees f. A keen gardener told me that they had failed to grow sweet peas. Although a lot of European flowers do well there. The farmers who used to grow opium were encouraged to grow our flowers instead for export and the displays in the flower markets are fantastic all year. I never saw sweet peas though.
As you know, our summers are long days and short nights.
It occurs to me that sweet peas might have a built in light sensor to flower.
You might get some if you grow them in a heated greenhouse in very big pots.
