First off, I will say that I prefer 1-series bodies for daily use, I find them more comfortable to handhold for long periods (a few hours) with my usual everyday lenses. Those are lenses like the 24-105/2.8 and 28-70/2, so the 24-105/4L is ‘light’.
My typical use for the R8 while traveling does not involve holding it for long periods. It’s either in a shoulder bag and I take it out for some shots then put it back, or it’s on a tripod.
I’ll also note that I have a Really Right Stuff plate on the R8 – it’s the one for the EOS RP and it effectively extends the bottom of the camera by 9.5 mm (just like the Canon EG-E1 extension grip that also fits the R8). That extension gives my pinky a place to rest.
With all that said, I don’t find the setup to be front-heavy or ungainly to use handheld with lenses like the RF 24-105/4L, RF 24-240 or RF 100-400. It does feel front-heavy with the RF 28-70/2 or RF 100-500L, for example.
Hope that helps…