Well I do hope that Turkey is still intact for your trip ...
There is no way I'd be happy going there without the 5D, and I think the M would be a good companion for when your wife tells you it's time to put away the 5D. :-[ :-[
I was in Turkey a couple of years ago - took 5DC, 24-105 (& Zuiko 18mm, which I needn't have bothered with really)
My advice, for what it's worth - keep it simple - stick with the 5D.
I too am going on a trip next week and also intend to travel light..well, travel light != carry light
Basically, i'm still going to bring my 5D3 with my 24-70II and my 600EX flash..BUT those will be packed into the cabin luggage and not my backpack..
All i'm carrying on my back is my EOS M with the 22mm kit.
For me, i'm only going to bring out the 5D when i know i'll need it…it's a matter of pre-planning the locations I'll be visiting or if i know there'll be a car to ferry me around, i'll bring along the 5D.
For most cases, i believe the M is enough.