So far, all the models appear to be warships. But if you want to scratchbuild a sailing ship I would really suggest a merchant ship because they are far simpler. Hardly any fancy decoration and no guns or stern windows in most cases. Here is the Norwegian barquentine BARDEN that I completed last week. I know that you are talking about large models and this is a miniature. But the plans are available large scale from Brown, Son & Ferguson, Glasgow under the name Scandinavian Barquentine. I would think that something like this is ideal for a first attempt at a large scale square rigger. It would be easier to radio control as well, because the main & mizzen could be left to their own devices and only the yards on the foremast swung by R/C.
Bob