I'd be up for a slice of that, Andy. I do a mini weekend 'tour' every year on the 3XV, but it's prob only about 500 or 600 miles or so over the weekend (the RD rally in Derbyshire). Travel light, and touring on a little stroker is not necessarily uncomfortable.
The Plymouth/Santander ferry crossing sounds like a good idea too though. Arguably better than flogging it there and back along the inevitable motorways though France. Or maybe even ride down to Spain but take the ferry back? It's always more fun going than it is riding home, and it's less hassle if anything goes pop if you know that you have a ferry booked back to Blighty.
Either way, it sounds like a plan to me.
Wb