Thats surprising – one of our plastic garden stores does occasionally get condensation. You would think the plastic would have the same problem as the POD. Perhaps its borderline. I think I would take the precaution of lining to some extent – if it doesnt make the whole thing too heavy.
Yeah, some spiders must be very keen astronomers, they gravitate to optics. Rather like the family of earwigs that once took possession of my Fullerscopes MkIV mount….