Not sure if you have these in Singapore but B+M has rear lights with built in reflectors for standard mount, normally on rear rack which as I remember you do not have mount points on yours.

You can also use strap-on reflector mounted on seat post. SON also has new rear light model which mounts directly to the rear rack tube. They also have models mounting to the mudguard. On the same page you can see their other models along with reflectors/adaptors to couple with standard rear light mounts. These are not cheap though but top quality products. Here is the link