The adaptor we sell has a round male 13 pin socket and a 7 pin flat female plug and is suited to European and English vehicles with 13 pin round female sockets that are being hooked up to New Zealand trailers, boats and caravans with 7 pin male flat plugs. Our adaptor does NOT fit European and English Caravans and Boats with a 13 pin male socket.
It would be easy for us to make up 13 pin socket adaptors for European Caravans but the problem is that we can not source female sockets that are configured for fitment on an adaptor; all the female sockets sold in new Zealand are only suitable for mounting on a hard surface.
Until a suitable female socket becomes available locally, we can only suggest you fit a female socket on your caravan and use a 13 pin round male socket to 7 pin male flat plug adaptor we have available. Total cost would be nz$108.00 inc gst plus freight if applicable.
Hope this helps!
p.s. Have you seen this? https://megatyre.co.nz/content/2013/07/trailer-plug-adaptor-13-pin-round-to-7-pin-flat/