If I understand, it involves changes to the DB server? That would be a show-stopper for me.
Haven't used Chartio in a while but when I did the reverse ssh tunnel was just a standard reverse ssh that you could deploy on any server in your vpn. It doesn't have to be on the actual db server, it could be on its own server acting as a bridge between Chartio and your db. Also, you could use whatever ssh client you wanted - you didn't have to install anything from Chartio in your vpn.
This made me think id need to do something on the DB server which I cannot:
“On your database server, run the following to install autossh”