I would take the R6 and I would prefer wider aperture over zoom range, on the basis I assume you will be able to be relatively close to your subjects at least most of the time, you will probably be shooting in low light some of the time, and sometimes you might have a messy background which you'd like to blur. I also assume you won't be carrying gear too far at a time and you will have somewhere to store gear when you are not using it, so weight isn't a big concern. So, I would take a 24-70 f/2.8 over a 24-105 f/4 if I had it, although if I didn't I would just take the 24-105mm. The other thing I would bring though, if I had one available, is a fast prime. In my case, I would take a 35mm. I might even end up taking a second prime too, although if I had a 24-70 or 24-105 and a 35mm, that really should do!
I like the idea of the RF 16mm as a UWA option. I do own the RF 35mm also so would not take much more to bring.
