I really like telephoto and my experiences with the following combos are good:
5D + 100mm Macro & EOS M + EF-M 22mm or
5D + 70-200 f/4 & EOS M + EF-S 10-22mm via adaptor
5D + 100-400 ii & EOS M + EF-M 11-22 or
5D + hypothetical 40-200 f/4.0 + EOS M + EF-M 11-22
EOS M is a very comfortable body for seldom used lenses because it fits with lens in a lens compartment of a photo backpack. And you have the option to use the tele on APS-C.
Another idea would be to use the EOS 100D (SL1) instead of the EOS M to stay into "one" system.
In your case:
For hiking perhaps your 60D with 70-300 zoom plus the Olympus compact might be a good "team" ...