afaik no that's impossible without modifications of the customers OpenVPN software itself (they would need firewall/iptable rules for NAT, impossible to set via

afaik no that's impossible without modifications of the customers OpenVPN software itself (they would need firewall/iptable rules for NAT, impossible to set via OpenVPN config). That's exactly why it's a bad sign if a VPN provider doesn't just give you VPN configuration files.