i didn't do this, but i think it's a viable solution.
here is the theory, for example, one 10K account, assume maxium loss 10% (i.e. SGD appreciated 10%), leverage 50, good for a 100K notional hedge
when open, 2k margin used
if sgd appreciate 8%, 10k margin used. (need pop up money to account, since you are hedging you should 'make money' in u sgd assets')
if sgd depreciate 8%, e.g., you account will value 10K + 8k unrealized = 18k. 8k is the hedging gain.
so be careful on your notional hedge amount and margin level.
and counterparty risk need attention as well.
btw, i personally feel rmb/usd rate will be much more stable than Aus/SGD or EUR/SGD. if you short AUS long USD to hedge your SGD, it's cross-hedging which abviously introduces more uncertainties.
cross-hedge when 1) direct hedge not possible, or 2) you try to make extra profit (other than hedge)
