I completely get it. You need to get a Gore-shelled down bag
I used Goretex (not Dryloft) covered down bags from 1982 to 1998. They limited the comfort range of the bags slightly, but man did they work in the chit. I don't use them anymore and I think only Dryloft is available these days. $$$
Apart from that, if you're going single-walled and floorless in your corner of the world, I think you're smart to use a synthetic. Me, I'd do a tent and down, but we're arriving at the same destination.
Again, my only point was down can work perfectly well in wet conditions depending on the operator.
