The above advice is good, but repeat after me...dark, dry, cool...

I've camped alot with guitar and/or mandolin. DON'T leave them in an automobile. DO leave them cased, covered in something light coloured and reflective, and on the ground is cool (literally) if it's not wet. The cabin (that's camping?) is fine, but cool and dry is important, and out of direct sunlight, even if it's through a window. A large ziplock bag for accessories and sheet music is also a good idea. I love gigbags and often that's all that's required, but if there's space, hard cases are good and can serve to carry other stuff.

Dark, dry, cool.

Peace, Mooh.