This should be interesting... I land in SIN around 2:00 AM on April 5th on a non-*A carrier. I plan to spend the night in SIN, then fly to KUL the next day to check out the Formula 1 Grand Prix and come back to SIN the same evening (flying to KUL and back on non-SQ carriers).
The following day (April 6th), I fly SQ business to BKK.
Since I'm able to get my BP 48 hours in advance, I plan to go to the SKL upon my initial arrival in SIN on Apr. 5th, and using the SKL then (2 AM April 5th), as well as (hopefully) at the SKL lounge in KUL the evening of the 5th (the evening before my SQ SIN-BKK flight).
Should be interesting to see if that will work, especially at the KUL SKL lounge, since I'm not flying SQ from KUL (but rather from SIN the next morning). Do you think I'll be able to get in these various SKL lounges?