Having lived on the rock I can appreciate the difficulty you're having. If I was back there with my 911 I'd take it to someplace like Krown and have her treated prior to storage. The thin oil they use gets into all the little nooks and crannies displaceing the water plus it'll also discourage the neighbourhood stray cats from taking up residence
Treat your leather with a good leather treatment product to protect it. Considering the humidity there I'd fill the gas tank so theres not much airspace in it, Add some fuel stabilizer to keep the varnishs and gums from forming and you ought to be OK.