> just to exclude 129.69.90.133. This is .... not nice :-(
You don't need to do this. Just use your current route, but add a host
route to route OpenVPN payload packets directly to the next hop gateway:
push "route remote_host 255.255.255.255 net_gateway"
remote_host should substitute to 129.69.90.133 and net_gateway should
substitute to the machine's default gateway.