If you are going to connect to TPE, then ask QF in MEL to only tag your bag to SIN. Then in the morning, get the MH agents to tag your bag to KUL then TPE. There's less chance of your bag getting lost that way. Having said that, the agent should be able to tag your bag all the way to TPE from MEL if you ask nicely.

If you aren't going to TPE, and you're finishing your journey in KUL, then ask the QF agent in MEL to tag your bag to KUL, and just take what you need for the overnight in your hand luggage. Unless you have something not permissable in hand luggage that you need in SIN, it'll be much easier for you not to worry about your luggage for the transit, especially as your overnight stop is preyty short, and your SIN-KUL flight is really early.