The shorter photoperiod will definitely help to trigger dormancy. If you can place the plants on the east or northeast side of a building, then they'll get morning sun but be in the shade before mid-day. That will help with the process, too. Hopefully, you'll see Sarracenia growth slow down and then stop; the flytrap growth may slow down a lot
and produce short, wide, ground-hugging petioles. Those are signs of dormancy.
If I lived in the tropics, then I would try Sarracenia species (and hybrids) that are from the Gulf-coast region of the U.S.:
- S. alata
- S. flava (the northwest-Florida plants, as opposed to those from South Carolina, North Carolina, and Virginia)
- S. leucophylla
- S. minor
- S. psittacina
- S. rosea
- S. rubra ssp. gulfensis
These species are used to mild winters where it usually gets just cool: bottoms-out at 7-10°C/45-50°F just before dawn, warms up to 15-21°C/60-70°F in late afternoon. They are more likely to adapt to life in the tropics.