You should buy the 500 or 800. They'll go well w/ your equipment. In fact get both so u never run short.
They don't have Sherpas in Iceland.
5DS R, 7D II, EOS-M, Powershot G3 X, 300/2.8 II, 1.4xTC III, 2xTC III, EF 1.8 STM, EF 70-200/4 IS, EF 24-105, 15-85, 100-400 II, Sigma 10-20, Sigma 150-600mm C, EOS-M 18-55, f/2 22, 11-22