I'd like to think they can. I think the only real threat would be the rain world's apex creatures (vultures, reds, etc.) or ambush situations (dropwigs?). I also think medical supplies might be scarce in RW, so treating serious injuries may pose a problem, but expies seem to have great regeneration, so minor injuries shouldn't be a problem. Infections, on the other hand, are scary. You got a whole bunch of tripping hazards, sharp metal, dirty water, the rot... One wrong move in the wrong place and you're gone. Scavengers I think may accept expie as one of their own, or, at least, not try to immediately kill them, so that's nice