It's three years since I made a similar trip, my experience was that my RIB insurer, GJW as i recall, were happy to cover the boat for travel to Mainland Europe, I think it was just a case of letting them know when I was travelling and for how long. I imagine that most insurers will offer something similar.
Also carried the original invoice and certificate of conformity for the boat, the invoice was to prove ownership and to evidence that VAT had already been paid.
Having said all of that, no one checked the paperwork at the border or where we moored in Spain.
__________________
|