just realised that the easiest way to gain ST Elite+ is fly DPS-LOP by Garuda Indonesia
domestically they only sell Y subclass, which will result in 3 freq in GA Miles in a segment.
STE+ in GA Miles is Platinum tier, which requires 65,000 miles or 65 freq.
DPS-LOP is now about USD 65. it will need 11 rt trips, for total amount of USD 715.
catch: GA Miles is not really useful for redemption (high redemption rate)