The RYA notification does not mention the T2L form which people sailing in Portugal use to deem their boats VAT paid. It was the subject of an article published in the RYA magazine about a year ago. This form might be a aolution to the problem.
I attended a Cruising Association talk on this topic, and then went and looked at how to apply for such a thing. It looks incredibly complicated to do, but very official looking when received. I wonder if anyone has attempted such a thing or knows of a simple guide to doing so ?