Following Jims suggestion, I am quite taken with the Mk3, more in keeping with the original plan and retaining the balance I am looking for.
As far as your 3" semi Jim, I think that would be a really cool project, so different to the usual. it really appeals to my sense of familiar but so different. Sort of midway between solid and acoustic.
Its quite odd but despite my love of the telecaster, the one I don't get on with is the Thinline, I had one but gave it away, I just didn't like it!. Your potential guitar would/could be full electric but also would have the depth for true acoustic (plus if it works out and you have the mould, you could make another! hint hint(especially as you are not in Oz!)