Boats on trailers usually go over on the Gry Maritha rather than the Scillonian.
The gigs all go over for the 'World' Championships on trailers.
In support of your proposal (I regularly nip over by sea), if you are tied to a specific booked week, the weather is likely not to play ball. I've known guys book a cottage over there for a week and have big problems either getting out or back when required.
When we make the trip out of Falmouth, we look for a weather window and then plan, you'd not have that luxury.
Stick her on the Gry.