"you have abstracted away the underlying connectivity issues" – Yes, but still if there is a long enough window of broken connectivity to the VPN, SSH connections may break because of low
ServerAlive* settings on the client or low ClientAlive* settings on the server, or because of TCPKeepAlive yes on any end and low /proc/sys/net/ipv4/tcp_keepalive_* settings there, or because of short ChannelTimeout and UnusedConnectionTimeout on any end. So if after hours SSH sessions disconnect despite reconnecting to the VPN then one should review all these settings.