My indoor props

You could always mount each one in a framed stand, like outhouse size with a roof to protect them. This would also allow you to light each one independently - for example, you could light them up in sequence so you don't actually see them all at once. Do you have an actual theme? If your doing a scene like Camp Crystal, then you could make each stand look like a camp hut. The grim reaper's hut could look more like a mausoleum. But if these guys are animatronic, then it's a bit of a gamble they're not usually of the quality that can take moisture, even indirect moisture.