Any external recorder will wipe this out. I use one all the time with the EOS R and the R never gets warm and the LPE6N battery runs for hours
The EOS R used a 1:1 4K crop to reduce overheating. The sensor readout for the R5 is a bit more of a challenge. It's the reason the Nikon Z7 and Sony A7RIII had to line skip instead of oversample like their lower megapixel counterparts.