Sell the R5 and get an R7 and R? Crazy?

Oops. I don't want to start a discussion on this now, and won't continue it, so I'll just comment briefly. You said you are satisfied with the noise performance of the R7, so that should be it. But if you are tempted by what you read on the Interwebs, you might want to read further. I could be mistaken, but my impression is that you still don't understand this quite right. Here are some reputable sources that have been thoroughly discussed in the the Photographic Science and Technology Forum:

Equivalence

What is equivalence and why should I care?

In the first link, search in particular for the following section.

Joseph James wrote:

8) Larger sensor systems have less noise because they have larger pixels / higher ISOs result in more noise [he presented this as an erroneous belief]

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mraifman wrote:

I would beg to differ that noise is not a function of the camera as sensors definitely dictate noise levels when controlling for everything else.

It depends on what you mean by "everything else".  Most people misunderstand this badly and think it means the same exposure.

Noise is mostly determined by the number of photons per duck, and that is entirely determined by the lens, except for minor (and usually unmeasured) differences in quantum efficiency.  Sensors differ in read noise, which can affect deep shadows but not much else.  The R5 and R7 have similar (not identical but comparable overall) read noise on an equal-area basis, when stated correctly in electrons.

Also, full frame cameras do provide nicer boken than crop sensors typically. Again, separate from the lens.

I don't know how it could be separate from the lens unless one compares incorrectly at different display magnifications.

However, don't disagree that lens choice is a big part of this.