iptables -t nat -I PREROUTING -d 10.10.10.11 -j DNAT --to-destination 192.168.0.11
But if I try, on said OpenVPN server itself,
telnet 10.10.10.11 80
This will not work in principle as you are trying another use case. In case you are going directly from openVPN server the proper chain would be iptables -t nat -I OUTPUT, while iptables -t nat -I ...