One problem I have with gpg, is that it requires having the private key wherever I am locate when I read or write emails.

I would prefer not to have my private key stored in more than one location. Preferably only ever have it located in one place (and an offline backup.)

However if I am traveling, on mobile, or whatever, then I either need to store my key with me (increasing the likely hood of being compromised) or access the machine which has my key, decrypt and write the response there.

What should be possible, is on my laptop or phone, or whatever, every time I need to access the private key, to ssh to the desired machine just when encryption or decryption is needed. Much easier to revoke and SSH key than it is a gpg key.

Why is there no simple way to do this. Is there and I just don't know about it. It seems like the only real way I would ever trust doing encrypted emails on my phone.