I play classical guitar and I live aboard. It is less humid than i thought it would be in my boat. But to be sure that I do not jeopordize an expensive instrument, I use my Yamaha CG-101 all wood laminate (ply) guitar. I've had no issues with it or my other solid top spruce that I had on board for 4 months during the hot and humid summer months.
Humid environments have far less damaging side-effects than the dry environments do.
My suggestion to you would be to go out and buy a nice quality low end guitar like the Yamaha for camping/boating. Both outings could involve things getting wet and thus make bringing expensive instruments not the best idea.