I found a plausible answer which did not work for me, but almost!

To start it up, follow this:

1. Install xpra both on the server, and on the client. On Debian-like OS it would be:

   sudo apt-get install -y xpra
   

2. Temporarily stop the Bitcoin Core daemon on the server:

   bitcoin-cli stop
   

3. Over the first SSH connection, start xpra on the server like this:

   xpra start :7
   

4. Over the second SSH connection, start bitcoin-qt on the server like this:

   DISPLAY=:7 bitcoin-qt
   

5. Connect xpra from the client to the server like this:

   xpra attach ssh:SERVER-IP:7
   

After you have finished your work, follow this:

1. Close Bitcoin-Qt on the client

2. Press CTRL+C in this window and close it:

   xpra attach ssh:SERVER-IP:7
   

3. Press CTRL+D in this window and close it:

   DISPLAY=:7 bitcoin-qt
   

4. Press CTRL+C in this window and don't close it:

   xpra start :7
   

5. Issue this command in the SSH session to the server:

   xpra stop :7
   

6. And finally start your Bitcoin Core daemon again with or without a wallet:

   bitcoind -daemon -disablewallet