[Closed] Sram X9 short cage with 42t Expander? Or smaller chainring?

Couldn't find anything, but does a 42t with short cage x9 work ok? (just worried the short cage won't have the range to fit the 42t?).

Currently running a 36t front with 11-36t rear on a trek remedy 9. Riding across the alps gr5 next month so figured I would want a littler gear! 🙂
Any particular brand to go for?

The alternative is to get a smaller chainring, but I wanted to keep the higher gears as I'm heading to morzine on the lifts adterwards. Would you get the expander, or get a smaller chainring (and then put the bigger one back on when I get to the proper dh stuff). Probably wouldnt use either the expander or 30t once I'm back, as my 36-36 gets me up everything anyway

Cheers!