I can't comment on the hocks, I think I remember prettylupin saying she put her bun outside as long as it wasn't pouring, but I think that was on grass.
One thing I will say is that Oidhche (our Rex) takes a lot longer to dry out than any other bun I've had in the past, so if it's actually raining I'd keep an eye on that side of things.
Edit: Found PL's comment