The idea that it's hard to get to the airport for a 9am flight is laughable. 1 hour is plenty in Singapore. A taxi or Grab takes 20 mins from downtown, a train no more than 40 mins and costs about 2 sing dollars. Everything will be running when you need to go. Or there are oodles of cheap hotels near the airport with free shuttles. Not the expensive one that is attached, the ones in the adjacent suburb. Any booking engine like Agoda will find them. (Flew out of Singapore this morning, a place I fly to often).