Is it possible to add a 'half night' stay at a hotel?

I'm planning a stay at the IC Singapore. My conference ends at 530PM, and my flight out leaves 1050PM the same night. Of course late check out is only until 4PM. I am thinking of going back to the hotel after my conference, shower then leave the hotel around 7-730PM (I also wonder if the traffic around the area, going to the airport would be bad around that time?)