Revisiting this thread after 6 months because I have found very little clarity has been shed anywhere on the subject of vanning bikes into Europe without their owners present.
I have just come back from a trip to Spain, which involved me transporting my bike and 5 others in my van for the use of my friends and I for 4 days trail riding. PreBrexit I would have used the Portsmouth Le Havre boat, and driven down, but having "heard" tales of mixed receptions from French Customs officers, and "better" results from Spanish ones, I chose Portsmouth Santander. Other internet chat mentioned taking proof of intent to use the bikes for personal transport for use on holiday, letters of authority, etc etc...
My experience is this:
On arrival in Santander, the immigration officer looked in the back of the van, and I was directed into the customs check/something to declare area. There I had a long ish chat with the Aduanero. I had no documentation other than the registration documents (V5s)
He told me that one driver and a couple of bikes, one of which being the driver's own, would be accepted as private transportation, and basically overlooked. However, a large quantity such as I was carrying, is considered freight, irrespective of whether payment was involved, and as such a customs declaration is required. The declaration should be for temporary import, and would not require payment of any duty.
Rather than refuse me entry, fine me or make me fill out countless forms, the gentleman asked for 3 randomly chosen V5s, checked the VIN and registration numbers against the bikes, told me to do it properly next time and sent me on my way.
On my exit from Spain, a different agent asked for the customs paperwork, I explained what happened on the way in, and the original guy also meandered over to confirm my story. This time all 6 V5s were looked at to check they matched the bikes, but VINs were not inspected.
Of course, winging it like that is not recommended(!!) and I was given the distinct impression, through my half decent Spanish and the agents' half decent English (there was a short mutual alphabet pronunciation lesson over Y, F and W!) that they understand the confusion and lack of official guidance, but my sort of behaviour will not be tolerated for much longer.
Now the question still remains: What sort of customs declaration is required?
Whilst in Spain I met a chap who gave me the web address of a company who deals in ATA Carnets - which appear to me to be for all sorts of equipment temporarily imported into Europe (for example film industry equipment, unregistered vehicles etc) I have yet to contact them, but I understand the ATA carnet to be a different document to the carnet de passage en douane which people on this forum will be more aware of as the document required when countries don't have a TViP system (temporary vehicle import permit)
The clouds have yet to clear on this subject, but I thought my experience should be recorded if only to confirm that people planning to van multiple bikes into Europe DO have some hoops to jump through.
Incidentally, one of the friends on my trip recently took a vintage Frazer Nash race car to Ireland (Republic of) for a mate of his, and had broadly the same experience, except his customs inspector threatened an on the spot duty fee, which for such a vehicle would have been a substantial sum!
The company dealing with ATA Carnets, for anyone wanting to investigate for themselves, is
www.boomerangcarnets.co.uk