So your best choice should be setting up a simple PPTP server (one that can be accessed by default Wiindows and MacOS VPN clients) and also make sure to add a /ip firewall filter rule that would allow the VPN subnet access to port 80.
Then just share the VPN credentials with your support and they will be able to access your web config.
Basically, this is what you want https://rbgeek.wordpress.com/2014/08/26/pptp-server-setup-on-mikrotik/