> copy-pasting them to remote machine is more reliable, This has basically nothing to do with the underlying cryptosystem. Instead of explicitly configuring R

> copy-pasting them to remote machine is more reliable, This has basically nothing to do with the underlying cryptosystem. Instead of explicitly configuring RSA keys, SSH could have been setup where you put their SHA256 hash in the authorized key file. (The pubkey itself would sent by the user at auth time and checked against its hash)