That sounds like a very interesting summer; made all the more so because Dumbledore and the Order don't suspect anything and Harry's taken care to hide what he can. I rahter suspect that his first days at Silvermoor should be quite interesting.
I did love Silvermoor's approach to concealing the school by using non-magical rather than magical means of traveling most of the way there. I agree, too, that the location is quite somewhere that you wouldn't expect a school to be; though that could also be a bit of further misdirection.
I''m waiting, like I'm certain 'most all of your readers are, for the pandemoium that breaks loose once it's realized on September 1 that Harry is not on the Express and that he's neither at his relatives nor anywhere else traceable.