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Buy a proper camera backpack waterproof All Weather, wear it in the front with your big back on the back while hiking in to base camp, then just carry your camera gear whilst on a photographic trek.
If you have an iPad subscribe to NPhoto monthly magazine & also purchase the Ultimate Nikon SLR Handbook for the iPad, you will find this material a superb reference library, to broaden your skill base and understanding of the Nikon settings.
My opinion, if you are serious and wish to develop this passion as a long term hobby, part time or full time income producing primary / secondary interest right through and into your retirement, then go for the best you can afford. Therefore go for:
D800e, D7100, 14~24, 24~120, 80~400G series Zooms, Carbon Fibre Tripod, good ball head, perhaps a good gimbal head, things like TC's can come later, just remember they loose contrast & resolution over quality primes or zooms.
If you are interested in travelling through Europe and often this is a once every 5 years or more, then this gear will reward you big time. There is no excuse of a tradesman being able to blame his tools for poor photos, just poor workmanship with this selection of quality camera gear.