some additional thoughts: even though you should be able to enter airside and access the MH lounge at the satellite building (lounge open 24hrs), it is a long time to be spending there until the next evening. I would consider getting a proper bed for the night - such as at the Aerotel, located landside at klia2.

The nap room at the MH lounge may be fully occupied by then and does not provide the level of privacy that you would get via proper rooms at the new Aerotel or at Tune Hotel (both landside KLIA2). Saves you from figuring out the transfer to klia1 at such early hours.